Dozens of teens robbed and assaulted passengers on a regional transit train in Oakland over the weekend in an apparently orchestrated attack, authorities said.

Witness accounts and surveillance video showed 40 to 60 teens jumping the fare gate at the Coliseum Station Saturday night, said Bay Area Rapid Transit spokeswoman Alicia Trost on Monday.

They entered a train that pulled into the station, grabbed bags and cellphones from seven passengers and then ran off into the neighborhood before transit police could respond.

Two people suffered minor facial injuries and were treated at the scene, Trost said.

Authorities were reviewing surveillance video to try to identify the suspects and planned to share it with city police, the Oakland school district and housing authority officials.

The transit system has experienced a series of robberies, prompting officials to step up patrols in recent weeks. They are tracking the locations of the crimes to increase the police presence at those stations, Trost said.

"We've had groups of people jump into BART trains, snatch cellphones and jump out. But a robbery involving 40 to 60 people is pretty rare," Trost said.

There were no reports of weapons used in the attack, she said.