Calvin Harris In Violent Car Crash ... Bolts from Hospital

Calvin Harris was involved in a terrible car crash Friday night, suffering injuries serious enough to require an ambulance ... but staying in the hospital just wasn't for him.

Law enforcement sources tell us ... Calvin was a passenger in a Cadillac SUV at around 11 PM when a VW Bug convertible driven by a 16-year-old girl crossed the center line, crashing into his vehicle.

The VW bug was filled with teenagers and the accident so violent ... one of the passengers who was sitting on her boyfriend's lap was ejected.

Calvin suffered a laceration on his face that was bad enough to require immediate attention. Paramedics took him to an L.A. hospital. We're told he wanted a private room, and when they said one wasn't available he hopped off the gurney and left ..."against medical advice."