STOCKTON, Calif. (AP) Kevin Curtis, a rookie safety with the San Francisco 49ers, will miss several weeks after tearing a knee ligament during Saturday's exhibition game against Kansas City.

Curtis, who was helped off the field in the second half, must undergo additional tests before the 49ers determine whether he'll need rehabilitation or surgery for the torn medial collateral ligament.

On Sunday night, coach Steve Mariucci called Curtis' injury "pretty significant. We're going to be without Kevin for a while. He's been doing a good job."

Curtis' injury leaves the 49ers thin at safety with three preseason games still remaining.

Safety Al Blades is wearing a protective boot after injuring his ankle earlier in the preseason, while veteran John Keith still hasn't recovered completely from a knee injury that limits his practice time and keeps him out of preseason games.

Tony Parrish and Zack Bronson - the two starters - and Ronnie Heard are the 49ers' only healthy safeties.

The information contained in the AP News report may not be published, broadcast or redistributed without prior written authority of The Associated Press.