Credit: Jon Kopaloff/FilmMagic

The good times came screeching to a halt on a party bus in Cleveland, Ohio on Saturday -- when actor Matthew Fox got into a reported fisticuffs with a female driver.

TMZ reports that the Lost star was briefly detained by police after allegedly punching a woman outside a bar. Fox apparently tried to board the party bus even though he wasn't a guest; the female driver then attempted to block his entry. Fox then allegedly punched her more than once.

The driver, named Heather Bormann, retaliated, punching Fox "in the mouth...causing a cut on the lip," a police report reads.

Fox was hand-cuffed and later detained by police; no formal arrest was made.

Fox's rep could not be reached for comment.

Bormann later told TMZ that Fox was intoxicated. "He just kept staring at me with his mouth wide open and not saying anything. I told him, 'You have to leave buddy. You are trespassing on my bus.'"

He then "leaned in and started punching my crotch and breast."

When Bormann hit back, she says, "This was my self-defense....This was the only way I could protect myself...from a man beating up on a woman."