Bus explosion in Tunisia

Ambulances and police vans are seen at the scene of a bus explosion in the center of Tunis, Tunisia, on Nov. 24, 2015.

Police and rescue forces at the scene of an explosion in Tunis, Tunisia, on Nov. 24, 2015.

An ambulance rushes to the scene of a bus explosion in the center of Tunis, Tunisia, on Nov. 24, 2015.

Tunisian police block the road leading to the site of an explosion on a bus transporting Tunisia’s presidential guard in central Tunis on Nov. 24, 2015.