Story highlights
- Two men questioned are let go without being charged, prosecutor's office says
- Two suspects at large after raid on a Brussels apartment tied to Paris attacks, official says
- Four people were arrested in Paris in terror plot raid, but authorities say no attack was imminent
(CNN)The police raid of a Brussels apartment tied to last year's Paris terror attacks turned up an ISIS flag, a Kalashnikov rifle and ammunition, but two suspects managed to escape after an intense, prolonged firefight, a spokesman for the Belgian federal prosecutor office said Wednesday.
Authorities killed one suspect in Tuesday's raid -- Belkhaid Mohammed, 35, an Algerian who had not been on authorities' radar before, spokesman Eric Van der Sypt said in a statement.
He said a special forces sniper killed Mohammed when he tried to open fire on police from a window.
The Algerian's body was found next to a rifle and a book on Salafism, a puritanical branch of Islam that dictates only the followers of the Prophet Mohammed practice the correct Islam. Authorities also discovered 11 loaded Kalashnikov magazines "and innumerable shell casings," but no explosives, according to Van der Sypt.
An intense manhunt followed Tuesday's operation in the southern Brussels neighborhood of Forest, which authorities connected to the investigation of the Paris terror attacks that killed 130 people in November.
One man was taken in for questioning during a subsequent house search Tuesday night in Brussels. And police also arrested an injured man who'd been taken to a hospital in Halle, a city about 12 miles (20 kilometers) south of Brussels.
But the Belgian federal prosecutor's office said Wednesday that both men were later let go without being charged.
What happened
The raid began around 2:15 p.m. (9:15 a.m. ET) Tuesday when four Belgian and two French police officers arrived at what was thought to be an empty residence in Forest, according to a senior Belgian counterterrorism official.
Instead, Van der Sypt said, "From the moment that the door of the flat was opened, at least two persons ... opened fire toward them."
Three officers -- including a Frenchwoman -- were hurt in the initial exchange of gunfire before managing "to retreat safely," he said.
Reinforcements arrived, with bullets flying back and forth for several hours. Another officer, from Belgium, suffered a slight injury to the head in the later exchange.
A Nigerian policeman inspects the site of a suicide attack by Boko Haram at a busy cattle market in the northeastern Nigerian city of Maiduguri in June, 2015. Boko Haram overtook ISIS as the world's deadliest terror group last year, according to the Global Terrorism Index, while Nigeria had the biggest year-on-year increase in terrorism, with deaths up more than 300%.
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In this image taken from social media, an ISIS fighter holds the group's flag as he stands on a tank, purportedly captured when they took over the town of Qaryatain, Syria. ISIS, along with Boko Haram, is one of two groups accounting for 51% of claimed terrorism deaths in 2014.
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A member of the Iraqi security forces fires ammunition in Baghdad in 2014 during a funeral procession of an Iraqi politician. The deadliest city in the world for terrorism is Baghdad. There were 2,454 deaths in Baghdad in 2014, with a death rate from terrorism of 43 per 100,000 people.
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Iraqi counter-terrorism forces patrol a street in Tikrit in April 2015, a day after the country's prime minister declared victory in the battle to retake the city from ISIS.
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An Iraqi Kurdish Peshmerga fighter prepares an ammunition belt as he guards a position at the frontline of fighting against ISIS militants near the northern Iraqi town of Sinjar.
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A Syrian family waits after arriving on the Greek island of Lesbos along with other migrants and refugees, on November 17, 2015. Ten of the 11 countries most affected by terrorism also have the highest rates of refugees.
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Two of the four wounded officers already had been treated and released from an area hospital as of early Wednesday, according to Belgian Deputy Prime Minister Jan Jambon.
Afterward, authorities found another Kalashnikov in a building near the site of Tuesday's raid. But other searches came up empty.
Belgian troops will help police in their anti-terrorism efforts, Prime Minister Charles Michel said.
There's no change in Belgium's threat level, now at its second highest, though the Prime Minister acknowledged Tuesday's bloody raid underscored the need to be on guard.
"The terrorist threat level is maintained at level three as yesterday's events confirm the threat is still real," Michel said.
French arrests
Four people suspected of planning a terror attack were arrested Wednesday morning in Paris, French Interior Minister Bernard Cazeneuve said.
The four suspects, three men and a woman, were taken into custody.
A source close to the investigation told CNN that police moved in to make arrests in Paris after individuals discussed launching an attack in the city. So far the plot appears to be only aspirational in nature. Police have not recovered evidence pointing to concrete planning, the source told CNN.
Cazeneuve, speaking to French media, said intelligence services are making arrests and carrying out terror-related investigations every day and called for "prudence." He confirmed that authorities found a starter pistol with one round but no other arms or weapons.
Belgium a focus
It's unclear what connection Tuesday's raid has to the November 13 carnage in Paris.
Belgium long has been a focal point for investigators.
A forensic scientist works near a Paris cafe on Saturday, November 14, following a series of coordinated attacks in Paris the night before that killed scores of people. ISIS has claimed responsibility.
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Police are out in force November 14 near La Belle Equipe, one of the sites of the terror attacks.
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Forensic police search for evidence inside the Comptoir Voltaire cafe after the attacks.
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Shoes and a bloody shirt lie outside the Bataclan concert hall on November 14. Most of the fatalities occurred at the Bataclan in central Paris.
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Security forces evacuate people on Rue Oberkampf near the Bataclan concert hall early on November 14.
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Medics evacuate an injured woman on Boulevard des Filles du Calvaire near the Bataclan early on November 14.
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Police, firefighters and rescue workers secure the area near the Bataclan concert hall on November 14.
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A man with blood on his shirt talks on the phone on November 14. He is next to the Bataclan theater, where gunmen shot concertgoers and held hostages until police raided the building.
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Police officers patrol the area around Notre Dame cathedral in Paris on November 14.
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Police officers patrol Paris' Saint-German neighborhood on November 14.
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Victims of the shooting at the Bataclan concert venue in central Paris are evacuated to receive medical treatment on November 14.
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A woman is evacuated from the Bataclan theater early on November 14.
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Forensics are working in the street of Paris after the terrorist attack on Friday, November 13. The words "horror," "massacre" and "war" peppered the front pages of the country's newspapers, conveying the shell-shocked mood.
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Rescuers evacuate an injured person near the Stade de France, one of several sites of attacks November 13 in Paris. Thousands of fans were watching a soccer match between France and Germany when the attacks occurred.
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A survivor of the terrorist attack in the Bataclan is assisted following terror attacks, November 13. The violence at the Bataclan, which involved a hostage-taking, resulted in the highest number of casualties of all the attacks.
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Spectators invade the pitch of the Stade de France stadium after the international friendly soccer match between France and Germany in Saint-Denis.
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Spectators embrace each other as they stand on the playing field of the Stade de France stadium at the end of a soccer match between France and Germany in Saint-Denis, outside Paris, on November 13.
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A body, covered by a sheet, is seen on the sidewalk outside the Bataclan theater.
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Rescuers evacuate an injured person on Boulevard des Filles du Calvaire, close to the Bataclan concert hall in central Paris.
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Wounded people are evacuated outside the scene of a hostage situation at the Bataclan theater in Paris on November 13.
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A medic tends to a wounded man following the attacks near the Boulevard des Filles du Calvaire.
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A woman walks past police and firefighters in the Oberkampf area of Paris.
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A riot police officer stands by an ambulance near the Bataclan concert hall in central Paris.
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Wounded people are evacuated outside the Bataclan concert hall.
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Police secure the Stade de France in Saint-Denis, north of Paris, following explosions during the soccer match between France and Germany.
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A wounded man is evacuated from the Stade de France in Saint-Denis, outside Paris.
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Spectators gather on the field of the Stade de France after the attacks. Explosions were heard during the soccer match between France and Germany.
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French security forces rush in as people are evacuated in the area of Rue Bichat in the 10th District of Paris.
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People leave the Stade de France after explosions were heard near the stadium during a soccer match between France and Germany on Friday. Paris Deputy Mayor Patrick Klugman told CNN President Francois Hollande was at the match and was evacuated at halftime.
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Victims lay on the pavement outside a Paris restaurant.
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Rescue workers and medics tend to victims at the scene of one of the shootings, a restaurant in the 10th District. Attackers reportedly used AK-47 automatic weapons in separate attacks across Paris, and there were explosions at the Stade de France.
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French security forces move people in the area of Rue Bichat in the 10th District. A witness told BFMTV that firefighters were on the scene to treat the injured.
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Two terrorist operatives phoned in orders from Brussels to those directly involved in the Paris attacks, according to a senior Belgian counterterrorism official.
These two had an even more integral role than Abdelhamid Abaaoud, the man long identified as the ringleader of the attacks, according to the official.
In his remarks Wednesday, Van der Sypt noted that authorities have searched more than 100 houses and arrested 58 people as part of the post-Paris probe. Another 23 people have been arrested "in linked investigations."
Fear of more attacks
Abaaoud was killed during a raid that collapsed an entire floor of an apartment building in Paris.
Yet others with Belgian connections and ties to the November attacks remain at large.
They include Salah Abdeslam, a Belgian-born French national who lived and spent time with Abaaoud in a Belgian prison. The trail for Abdeslam, one of the few alleged Paris attackers to escape alive, went cold in December, according to a senior European counterterrorism official.
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French sources close to the investigation said Abdeslam was not the target of Tuesday's raid.
Many of those tied to the Paris massacre lived in Belgium, and they're believed to have met there before planning attacks.
There is concern more individuals from the same place may be ready to launch other attacks.
