Update from LiveLeak:
Video starts immediately after the first shots were fired. SKIP TO 1:50 FOR THE FIRST OFFICERS TO ARRIVE.
First officers on the scene believed the shooting happened inside the building. An officer at 2:15 moves in to check the van, sees a gunman inside, and immediately starts running away. Gunshots from the van ensue and at 2:48 you can see muzzle flashes coming from the van.
The video ends when an officer orders those on the roof to leave.
The suspect, James Boulware, previously threatened to go on a shooting spree in 2013 when he was arrested for domestic violence and marijuana possession.
The armored van was purchased on eBay 5 days ago: