The crash was reported just before 6 a.m. near the intersection of Lake Merced and Font boulevards.
Police said the suspected drunken driver drifted into oncoming traffic and hit another car head on. The third car then struck the second car.
Four people in the three cars, all San Francisco residents in their early 20s, were injured, according to police.
One person was hospitalized with injuries that were not life-threatening and was later released from the hospital, police said.
The driver of the first car was booked for DUI and a second person was cited for possession of what appeared to be marijuana, police said. Their names were not immediately released.
