The shouting, punching and hair-pulling episode took place aboard a bus on Stockton Street in Chinatown and was posted sometime Wednesday. It's unclear what set off the argument between the two women, but it lasted several minutes and ended only when another female passenger intervened.

Muni spokesman Judson True said the bus driver did not report the fight as required, and now an internal investigation is under way.

A warning for viewers: The video is laced with both violence and obscenities.

Here's an update: The guy who shot the video, North Beach resident Jonathan Perel, contacted us with more details. He tells us the fight erupted after one of the women, who was carrying a bag, took up two seats, and the other woman tried to sit down next to her.

Read more: http://www.sfgate.com/cgi-bin/blogs/...#ixzz0TSa00WSx