The collision happened shortly after 5 a.m. at Broadway and Third Street, where one vehicle apparently sideswiped the other. The car with passenger-side damage ended up on top of the surging gusher after toppling the hydrant.
Los Angeles police and firefighters responded to the scene, shutting down Broadway as they treated the vehicles' occupants.
At least one person was placed on a gurney by paramedics, but details of possible injuries were not immediately available.
Water shot up into the air as a towing crew pulled one of the mangled vehicles off the geyser. A worker then backed a utility truck onto the spouting water.