Four homeless men have been beaten to death with a metal pipe as they slept in doorways and pavements in New York’s Chinatown, police say.
The suspect, who is also homeless, wielded the weapon and went on his rampage early on Saturday morning.
A fifth person was left with serious injuries, police said.
Police recovered the weapon, which was still in the suspect’s hands when he was arrested, officials said.
The motive appears to be, right now, just random attacks, Chief of Manhattan South Detectives Michael Baldassano said at a news conference, adding there was no evidence yet that the victims were targeted by race, age, anything of that nature.
Two law enforcement officials identified the 24-year-old suspect as Randy Rodriguez Santos.
The officials spoke on the condition of anonymity because criminal charges had not yet been finalised.
Santos was taken into police custody and police say he has been arrested at least a six other times in the past two years – three times on assault charges.
The one who survived the attack sustained severe head injuries and was taken to hospital in critical condition. Police planned to interview him as soon as possible, Mr Baldassano said.
Another homeless man who had slept in the area, Stephen Miller, said he knew one of the victims as kind and quiet.
“No one knew him by name, but we saw him every day,” Mr Miller said.
“At this point, I’m just sad. This guy never did anything. Just had a life to live. It sucks that he’s out here in the rain and everything, but it doesn’t mean he doesn’t have a life to live.”
The suspect’s mother, Fioraliza Rodriguez, 55, told local media she had kicked him out about three years ago.
He struggled with drugs, assaulted her and his grandfather, and stole from the family, she said.
I never thought he would kill someone, she said. I was afraid of him, though, because he punched me. That’s when I told him to get out of my house.
Family members told the newspaper that he started using drugs when he arrived from their native Dominican Republic about four years ago.
When I told him to leave, he came back and threatened me, the suspect’s mother said. He said when I go back to Santo Domingo, he’ll get people to cut my face.