The bus driver drove away after five to seven bullets were fired about 12:20 a.m., blowing out the bus' back window, the San Francisco Chronicle reported.
No one was injured by the gunfire, but four passengers said they were injured when the bus sped up and were taken to a hospital, the newspaper said.
Clarence Johnson, an AC Transit spokesman, said it wasn't known why the bus was targeted and no suspects had been identified.
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