It was another devastating injury for the ninth-year pro from Florida.
Peterson, who entered Sunday's game with 108 tackles, missed 11 games last season after tearing a chest muscle.
He was slumped over at his locker after Jacksonville's 24-17 victory Sunday and declined to comment. Several players and coaches stopped by to console him.
"He broke it in several places and the question will be whether or not four or five weeks from now he can play with a big club or not," Jaguars coach Jack Del Rio said. "We'll have to assess that. Right now, he's definitely going to be out for a few weeks."
Without Peterson, the Jaguars probably will move outside linebacker Daryl Smith into the middle and insert rookie and second-round pick Justin Durant into the starting lineup.
The Jaguars also could be without cornerback Rashean Mathis next week against Buffalo. Mathis strained his groin in the first half and did not return.
Copyright 2007 by The Associated Press
