On a day when the Cleveland Browns found that two of their players face multiple drug charges after being arrested on Monday night during a traffic stop, ESPN.com learned the club's pending legal problems are not limited to that incident.

Law enforcement officials confirmed for ESPN.com that Browns defensive tackle Gerard Warren, the club's first-round choice in the 2001 draft, faces at least one gun violation charge in Pittsburgh, where he was stopped Tuesday morning after attending a party hosted by Steelers wide receiver Plaxico Burress.

Earlier in the day, police in Cleveland said that fullback Mike Sellers and corner Lamar Chapman were arrested Monday night after a traffic stop and face multiple drug charges.

Warren is charged with possession of an unregistered and concealed firearm, a loaded .45-caliber pistol that was discovered in his car, and a police spokesman said that an investigation is continuing and that subsequent charges could be added.

The third player selected overall in the '01 draft, Warren was still being detained early Tuesday evening. He was to be arraigned later Tuesday night. The possession charge is a felony in Pennsylvania.

Browns spokesman Todd Stewart said the team is "aware" charges are pending against Warren but is awaiting further details. Stewart said team officials will not comment any further before Wednesday.

According to the police report, Warren was initially stopped at about 2:30 a.m. on Smallman Street, in the city's Strip District entertainment area, a resurrected eastside neighborhood that has become popular in recent years for its restaurants and clubs. The police spotted an empty holster in the car and then, during a detailed search, found the gun in a glove compartment.

At 6:23 a.m., Warren produced documents indicating that his brother, Corey, a police officer in Florida, purchased the gun for him. But there are no documents to indicate the gun is registered and police told ESPN.com that Warren conceded it is not.

A passenger in the car, Percy Blue, is charged with marijuana possession and four other passengers were not detained. Warren was accompanied to Pittsburgh by Cleveland tight end O.J. Santiago to the party, which was attended by several NFL players, including Tennessee Titans defensive end Jevon Kearse.

The former University of Florida star signed a six-year contract that included a signing bonus of $8.9 million and could be worth as much as $44.1 million. He has been a starter and has 24 tackles and two sacks.

The arrest almost certainly will put Warren in violation of the NFL's personal conduct policy and could bring league sanctions. Warren was fined $35,000 earlier this year for a hit on Jacksonville quarterback Mark Brunell.

Len Pasquarelli is a senior writer for ESPN.com.