There was a brazen attack at a busy BART station Wednesday night.
Witnesses said three teens beat a man just outside of the Colma station's fare gate, according to police.
The victim was found bleeding on the ground and was taken to the hospital. His condition was not immediately available.
A ticket agent called for help, but all three suspects ran away by the time police arrived.
It's unclear whether the victim knew his attackers or if they were trying to rob him, police said.
A surveillance camera captured the entire incident. Investigators are reviewing the video for a better description of the suspects.