A gunman wearing a bulletproof vest opened fire in Philadelphia on Monday night, killing four people and wounding two others, police said.
Police Commissioner Danielle Outlaw said at a news conference that all the victims were male.
The suspect was arrested in an alley without incident, Outlaw said. He had a bulletproof vest, multiple magazines, an “AR-type rifle,” a handgun and a police scanner, she said.
"At this point all we know is that this person decided to leave their home and target individuals,” Outlaw said.