NEW YORK — A man who allegedly killed three people in an apparently unprovoked stabbing in Manhattan has been taken into custody, authorities said.

Ramon Rivera, a 51-year-old non-resident man, was charged with three counts of first-degree murder as a serial killer after being taken into police custody on Monday.

The man with blood on his clothes is believed to be homeless and a resident of the Bellevue men’s shelter on East 30th Street.

The first victim, identified as Angel Lata Landi, 36, was stabbed in the stomach at 8:22 a.m. Monday in an unprovoked attack at the construction site where he worked on West 19th Street. NYPD said.

About two hours later, a 68-year-old man was fatally stabbed multiple times on East 30th Street, police said. While the family is expected to be informed, the identity of the deceased has not been disclosed.

The third victim, a 36-year-old woman, was captured around 10:55 a.m. from 42nd Street and First Avenue, police said. He suffered multiple stab wounds to his chest and arm and was taken to New York Presbyterian/Weill Cornell Medical Center, where he later died from his injuries.

An Uber driver witnessed the third attack and followed Rivera onto First Avenue, yelling out the window for pedestrians to help.

Witness Baha Biten said, “I’m walking with him, ‘leave it, man, it’s not worth it’.” “I told him ‘put the bag down, there will be police ahead’.”

Senior NYPD Officer Robert Garvey was there.

“I just heard a commotion, I went out, I heard what people were saying and I reacted,” Garvey said.

He stopped Rivera, threw away her purse and found not one but two knives. One of them was bloody. He was taken into custody at East 46th Street and First Avenue.

“If Officer Garvey hadn’t been there, these random acts of violence, this person probably would have continued these random acts of violence. So he saved the lives of his fellow New Yorkers,” Adams said.

Police said the 51-year-old suspect, who was staying at the Bellevue Men’s Shelter on East 30th Street, chose the victims at random.

Police said the man was captured near East 46th Street and 1st Avenue.

“He walked up to them and started attacking them with knives,” Chief of Detectives Joe Kenny said at a news conference.

Surveillance video obtained by Eyewitness News shows the man putting on his hoodie, skullcap and gloves, then taking a giant knife from his backpack, hiding it in his shirt and walking away.

Mayor Eric Adams said the suspect had been arrested eight times before, according to law enforcement, and was believed to have serious mental health issues.

“There’s a real question as to why he’s on the street,” Adams said.

Police said two bloody kitchen knives were seized.

“These random attacks left two innocent victims dead and another fighting for his life,” Kenny said. “We have a suspect in custody and we are not looking for anyone else at this time.”