People pray at the entrance gate of the Bardo Museum in Tunis, Tunisia, on Wednesday, March 18. Earlier in the day, at least 23 people were killed -- most of them tourists -- when gunmen opened fire in the museum. Michel Euler/AP
A person is taken away on a stretcher outside the museum. Hassene Dridi/AP
Bullet holes are seen in a bus window near the museum. Ahmet Izgi/Anadolu Agency/Getty Images
A helicopter flies around the museum, which is housed in a 19th-century palace and describes itself as "a jewel of Tunisian heritage." Its exhibits showcase Tunisian art, culture and history. Yassine Gaidi/Anadolu Agency/Getty Images
Tourists are moved away from the scene of the shooting. Ahmet Izgi/Anadolu Agency/Getty Images
Tunisian President Beji Caid Essebsi leaves a Tunis hospital after visiting those injured in the attack. Amine Landoulsi/Anadolu Agency/Getty Images
Security forces patrol around the museum. Ahmet Izgi/Anadolu Agency/Getty Images
The museum is evacuated by authorities. There was a significant number of foreign tourists at the museum at the time of the attack -- something that's not surprising, given its prominence in Tunisia and the fact that at least two cruise ships were docked in Tunis. Hassene Dridi/AP
A security officer holds his position near the museum. FETHI BELAID/AFP/Getty Images
Security forces secure the area around museum. FETHI BELAID/AFP/Getty Images
Police arrest a man they believed to be suspicious. Yassine Gaidi /Anadolu Agency/Getty Images
Police in plainclothes stop a vehicle as they secure the area around the museum. FETHI BELAID/AFP/Getty Images
Tunisian security forces secure the area around the museum. FETHI BELAID/AFP/Getty Images
Security forces take up position outside the museum. MOHAMED MESSARA/EPA
Police take up position behind a car near the museum. MOHAMED MESSARA/EPA