Bobbi Booker and her unborn baby lost their lives because of an idiotic game of one-upmanship.

Police said that Booker, 27, who was four months pregnant, died at 9:20 p.m. Monday at Albert Einstein Medical Center.

Doctors had tried to find a way to save the mother of two and her fetus since Sunday night, when Booker was hit in the side of the head with a stray bullet while her boyfriend, Michael Thomas, traded gunfire with Lamar Johnson, police said.

Thomas, 26, and Johnson, 22, were officially charged yesterday with Booker's murder and the murder of her unborn baby.

Homicide investigators said that the gunfight, which occurred outside the Queen Lane Apartments in Germantown, was simply an escalation in an ongoing petty feud involving Thomas, Johnson and several other men.

Thomas used a shotgun during the shoot-out, while Johnson fired shots from a 9-mm handgun, police said. Homicide Capt. James Clark has said that both men have "lengthy" criminal records.

Booker was inside the apartment building and was apparently hit by a stray bullet from the 9 mm when she walked by a window, Clark said.

Relatives of Booker, who left behind two small children, could not be reached for this story.

A handful of residents who were gathered in front of the weathered high-rise apartment building last night said that Booker was quiet and mainly kept to herself.

The apartment building, owned by the Philadelphia Housing Authority, made headlines in February when Craig Kelley, a veteran PHA cop, was shot while manning a lobby booth inside. Zahir Boddy-Johnson, 17, was later charged in the case.

Booker's slaying, meanwhile, called to mind the tragic Jan. 31 killing of Emine Hajredinaj, 20, who was 28 weeks pregnant when she and her boyfriend were shot in Frankford.

Doctors were able to save Hajredinaj's baby. Police have charged Tyree Bass, 23, with Hajredinaj's slaying, which reportedly had been motivated by an argument. *