Four men died in separate shootings during a nine-hour stretch Wednesday night into Thursday morning, including a 22-year-old man killed in South Philadelphia in a fight over his backpack.

Shortly after 4 a.m. Thursday, two men with bikes were hanging out in the 800 block of Watkins Street when a third man on a bicycle rode past them and then turned around and tried to take the backpack from the victim, Chief Inspector Scott Small said.

"The victim resisted and put up a fight," Small said.

The shooter, described as a man in his 20s, pulled out a small-caliber, semiautomatic handgun and fired three times, hitting the victim once in the back.

Medics took the victim to Thomas Jefferson University Hospital, where he was pronounced dead at 4:36 a.m. A police source identified him as Gabino Aparicio, 22.

Aparicio worked for several years as a bar back at Public House, on 18th Street near the Parkway. A coworker said his full name was Jose Gabino Aparicio.

The shooter left his bicycle behind and ran east on Watkins with the victim's backpack and mobile phone, Small said.

The bicycle was to be examined for fingerprints and DNA evidence, Small said, adding that residents in the neighborhood would be asked if they recognized who usually was seen on the bike.

Investigators also recovered surveillance video recorded from private cameras in the area, Small said.

On Wednesday night, the first of the four homicides happened near the victim's home in Kingsessing. Raheem Williams, 26, of the 5600 block of Beaumont Avenue, was fatally shot in the chest about 7:20 p.m. He died at the Hospital of the University of Pennsylvania at 7:44, police said. No motive was given for that shooting.

Justin Carter, 20, of the 2200 block of Moore Street, was fatally shot in the back about 9:40 p.m. on the 2500 block of Emerald Street in Kensington, police said. Carter died at Temple University Hospital at 10 p.m.

No motive was reported in that shooting or the next one, in which a 36-year-old man was shot to the back and lower extremities in North Philadelphia. That shooting happened on the 2800 block of Taney Street about 12:20 a.m. Thursday, and the victim, whose name was not released, died at 1 a.m. at Temple. @sabdurr

Inquirer staff writer Robert Moran contributed to this article.