Three males were in the car, and one from the front passenger seat, later identified as Pratt, ran away with an officer in pursuit, police said.
Pratt ran into a dead end in an alleyway between Pemberton Street and Cedar Avenue, police said. During a struggle, Pratt pulled the officer's collapsible baton from his belt and tried to grab the officer's Taser, police said.
The officer then fired three shots, striking Pratt twice in the chest, police said. Medics pronounced him dead at the scene.
After the shooting, police searched for a gun that he might have tossed while running but did not find one. At a news briefing that night, police did not assert that he was armed.
Zakia James, 29, Pratt's cousin, said Friday that the encounter as the police described made no sense. She wondered: Why would Pratt fight an officer who did have a gun?
Pratt's older brother, Mikael, who is in the Army, also was in the car, James said. After being questioned by police, he went to the family's home in the 100 block of Conestoga Street.
He told the family the car was pulled over for making what police said was an illegal turn on a red light, James said.
The officer told the men in the car to step out, and, "at that point, for whatever reason, Hassan took off running," James said.
The driver of the Ford sped off and was still at large Friday night, police said.
Pratt had no children and had never married. He had a girlfriend whom he stayed with sometimes in Northeast Philadelphia, his family said.
He was employed as a maintenance worker at the ShopRite at Penrose Plaza, James said.
His family said he liked to joke and was protective of his younger relatives. He was about 5 feet, 10 inches tall and weighed 325 pounds, said another cousin, Azena Ferguson, 28.
After she learned about the fatal shooting, Ferguson said, "I kept calling his cell because I didn't want to believe it."
Contact Robert Moran at 215-854-5983 or firstname.lastname@example.org, or follow @RobertMoran215 on Twitter.