I watched the videos that Peace linked to, and played them over and over. There are two scenes- same scene but one is from farther away.

In the upper video this is the sequence:

Police car going through intersection at 2:04 on the video clock
There is a white streak traveling from right to left at 1:42
(Adding to the confusion a car races past the building at :25.)

In the lower video this is the sequence:

Police car in intersection: 3:11
Streak: 2:56

I don't understand the discrepancy of time: 22 seconds versus 15 seconds. Even allowing for camera speed differences, that seems over-much. Anyone have any ideas?

NOTE: It definitely appears that the streak is traveling directly at the spot where, less than a heartbeat later, there is a tremendous explosion.