(CNN)At least 273 people have died and 2,000 have been injured in the unrest that's rocked Nicaragua since April, according to the human rights arm of the Organization of American States (OAS).
The death toll includes two men killed Friday night in Managua in an hours-long attack by pro-government forces on protesters at the National Autonomous University of Nicaragua, the strongest protest holdout in the capital, said Paulo Abrao, executive secretary for the Inter-American Commission on Human Rights (IACHR), part of the OAS.
The protesters, who the government labeled as terrorists, had sought refuge inside a Catholic church and at least one of them died inside the parish as the church was hemmed in by gunfire, Abrao said.
The standoff at Divine Mercy Church was the latest in a series of violent clashes that started in April when the Nicaraguan government announced changes to the social security system regarding pensions.
President Daniel Ortega, who is been in power for 11 years, backed down a few days later, but the government's heavy-handed repression of the protests and the rising death toll ignited a national movement demanding Ortega's resignation.
The government puts the death toll at 51, including four policemen who died last week in the department of Rio San Juan. The government also has said some National Autonomous University students are hiding weapons inside the school to assault pro-government groups.
During a recent standoff at a Catholic church in Diriamba, south of Managua, the government made similar claims and said the church was allowing protesters to hide guns inside. The Catholic Church of Nicaragua denied the allegations.
The OAS held two emergency meetings last week to discuss the ongoing violence. Argentina, Chile, Colombia, Paraguay, Peru and the United States demanded an end to the repression.
The secretary-general of the OAS, Luis Almagro, proposed early presidential elections as a way out of the crisis. The government of Nicaragua rejected the request.
Bishop Silvio José Báez tweeted the news of Friday's attack as it started around 8 p.m. ET (6 p.m. local time).
"They're shooting at the Divine Mercy parish! There is a priest inside and several wounded. Stop the repression!" he tweeted. Minutes later, Báez tweeted that ambulances and first aid teams were not allowed to attend to the wounded inside the church.
Abrao said by telephone that at least 100 students were able to hide inside the church along with three journalists: Sergio Marín of La Mesa Redonda, Joshua Partlow of The Washington Post and José Noel Marenco of 100% Noticias.
According to Marenco, 15 students were shot. The images he shared online showed a gruesome siege in the middle of darkness.
A group of volunteer doctors, part of a permanent medical guard inside the church, treated some of the injured.
Marenco said other injuries were too severe and required hospitalization.
In the middle of the attack, representatives from the church, including Cardinal Leopoldo José Brenes Solorzano, members of the Inter-American Commission on Human Rights and members of the Red Cross mediated with pro-government groups outside the parish, which led to the entrance late Friday of ambulances and emergency services.
The majority of students and two of the journalists were not able to leave the church until Saturday morning, according to one of the trapped journalists and local media. The Rev. Monsignor Waldemar Stanislaw Sommertag, the Pope's envoy to Nicaragua, had to escort them out.
