PITTSBURGH -- Pittsburgh police have charged a 20-year-old woman with criminal homicide in the shooting death of her boyfriend on a downtown sidewalk.

Police said Ciara Roberts, of Baldwin, was arguing with her boyfriend, Chondale Terry, 28, late Saturday night.

Police allege that Roberts became angry when Terry walked away from her, and she caught up with him, pulled out a revolver and shot him in the chest in the 400 block of Wood Street.

According to the criminal complaint, a witness stated he "was several feet behind Roberts when he observed her remove a black revolver from her purse. He also observed her loading the gun as she was walking. (He) then observed Roberts remove the gun from her purse and shoot Terry one time in the chest ... then observed Terry fall to the ground."

Police said Roberts attempted to escape on a Port Authority bus before witnesses got the driver's attention and the vehicle was stopped.

Terry was taken to UPMC-Mercy Hospital, where he was pronounced dead at 12:19 a.m. Sunday.

A listed number for Roberts could not be found Sunday and it was unclear whether she had an attorney.

The shooting happened at about the same time a teenager was shot and killed in Pittsburgh's Hill District.