Chinese woman fighting with Black woman over a seat in a San Francisco muni in Chinatown.
San Francisco Municipal Railway officials said they were investigating a brawl between two women passengers on a Muni bus Wednesday that apparently went unreported by the bus driver.

The assault on the 20 Columbus line as it passed through Chinatown was captured on a cell phone video camera and posted to YouTube.

The video is laced with both violence and obscenities involving the pair.

"Our operators are required, by rule book, to report any assault that's occurring on a vehicle," said Muni spokesman Judson True, who acknowleged Thursday that the transit agency's records don't reflect any confirmed calls about the incident to either Muni's central control or to the police.

True said it was possible the driver wasn't aware of the fight because that particular bus is 60-feet long.

The man who shot the video of the incident, Jonathan Perel, told San Francisco Chronicle columnist and CBS 5 contributer Phil Matier that the fight erupted because one of the women was taking up two seats and wouldn't let the other one sit down.

"Just another day on Muni," Perel can be heard saying on the video he shot. Perel said he was assaulted a couple weeks ago while riding that same Muni line.