This bloody aftermath of a shooting in Karachi that killed three Sunni Muslim leaders.

Their deaths --- are believed to be part of a tit-for-tat escalation in violence between Sunnis and Shi'ites here.

The group, which included several top clerics, were shot inside a van they were traveling in. Surveillance video from the scene shows the suspected gunman approaching the vehicle, reaching inside several times before fleeing on the back of a nearby motorbike.

Police say attacks like this one are on the rise in Karachi.

Hundreds of mourners gathered for their funerals.