This happened yesterday and somebody was arrested. It look s like it might have been a robbery that started near 6th and stevenson and then chased down Stevenson toward 7th. The video shows the thief running down Stevenson carrying a white box being chased by somebody and then the police show up in seconds. There is a small boom sound in the video just before the chase, could have been related (car window smashed maybe)
the sequence starts at 1 minute in this 7 minute video
Watch live video from 6th and Stevenson, San Francisco on Justin.tv
and then a few second later
