PITTSBURGH -- Former lightweight champion Paul Spadafora was arraigned Monday on charges of attempted homicide and aggravated assault for allegedly shooting his girlfriend after an argument over two flat tires.

The 28-year-old boxer posted $50,000 bond and was released Monday night after spending most of the day in jail. The woman was hospitalized in critical condition, according to family members.

Spadafora's attorney, William Difenderfer, would not comment as he entered the jail Monday and didn't return phone messages.

Spadafora is accused of shooting Nadine Russo, 20, while outside a gas station Sunday in McKees Rocks, just outside of Pittsburgh. A witness told police that Russo drove Spadafora's vehicle over a concrete median, damaging the vehicle's tires. Spadafora then became upset, according to a police affidavit.

Spadafora was questioned after the shooting but was released because there was not enough evidence to press charges, Allegheny Police Sgt. Christopher Kearns said. He was arrested later following a traffic stop near his home in Moon Township, police said.

The former boxer is also charged with recklessly endangering another person and violation of firearms laws.

Spadafora was arrested last week on charges of public lewdness and intoxication after officers said they spotted him urinating on a Pittsburgh street.

Undefeated as a pro, Spadafora won the International Boxing Federation title in 1999 and successfully defended his title nine times. He has a record of 36-0-1.

Spadafora gave up the 135-pound title in June, saying he wanted to move up to the junior welterweight division. In his last bout in March, Spadafora fought Leonard Dorin to a draw. He was heavily favored to win the match.