Updated July 4, 2023 at 7:43 AM ET

Five people were killed and two others injured Monday night when a gunman wearing a bulletproof vest opened fire in a Philadelphia neighborhood, police said.

Three of the dead victims were men who ranged in age from 20 to 59, Police Commissioner Danielle Outlaw said at a Monday night news briefing. A fourth deceased victim was a male believed to be between 16 and 21, police said. Two boys were injured, a 2-year-old and a 13-year-old, said police, who added that the shooting took place in the Kingsessing neighborhood in southwest Philadelphia.

Police later announced that a fifth victim had been found. He was chased into his home and shot to death.

One suspect was taken into custody, Outlaw said. The suspect was wearing a bulletproof vest, with multiple magazines in the vest, she said, adding that the suspect also had a scanner, an "AR-style rifle" and a handgun.

Outlaw said the crime scene was a two-by-four-block area that had 50 spent shell casings. Police were still seeking a motive, she added.

"There are several scenes out here," Outlaw said. "We're canvassing the area to get as much as we can, to identify witnesses, to identify where cameras are located and do everything we can to figure out the why behind this happening."

"Horrified by reports of a shooting in Southwest Philadelphia," Mayor Jim Kenney said over Twitter.

Monday's violence came a day after a shooting took place at a holiday block party in Baltimore that killed two and wounded 28 others.

At least 339 mass shootings have taken place in the U.S. so far this year, according to the Gun Violence Archive. The archive defines a mass shooting as one where at least four people are shot, not including the shooter.

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