Three fatal shootings - two of them blocks from each other in Southwest Philadelphia and one in the Frankford section of the city - have been reported since Friday.

Police said they responded at 7:40 p.m. Friday to a shooting in a home in the 6000 block of Duffield Street, where they found Xiangzhen Lin, 25, dead from a gunshot wound to the head.

Police believe she was killed after an argument and have a suspect in custody.

A 38-year-old man who was fatally shot Friday night as he was sitting in his Mercedes in 5700 block of Rodman Street talking on a cell phone was identified as Stefon Shores of the 5700 block of Cedar Avenue.

Shores was shot shortly after 10 p.m. Friday. He was pronounced dead at 10:45 p.m. at the Hospital of the University of Pennsylvania.

Police are looking for a man who was on the street talking with Shores at the time of the shooting.

Early Saturday morning not far away, in the 5700 block of Christian Street, police found Khalil Thrower, 19, with a gunshot wound to the chest. He was taken to the Hospital at the University of Pennsylvania, where he later died.

Police did not have any suspects in the Southwest Philadelphia shootings, but they believed the cases were related.

Contact staff writer Mari A. Schaefer at 610-892-9149 or mschaefer@phillynews.com.