Mel Gibson -- Rear Ends Driver in Arizona

Mel Gibson caused a minor traffic accident yesterday, when his front bumper met somebody's back bumper in Phoenix, Arizona.

We're told no one was injured -- a cop came to the scene but no one was cited. Both vehicles sustained minor damage. After exchanging insurance information, both parties went their separate ways.

We're told Mel is in town to visit his father, who is hospitalized in Phoenix.

Mel hasn't had the best luck on the road, just last year he crashed his 2008 Maserati in L.A. But cops say he acted like a total gentleman after the wreck.