A man has been arrested after allegedly killing two people and injuring a third in an apparently unprovoked stabbing in Manhattan, authorities said.

The first victim, a 30-year-old construction worker, was fatally attacked on West 19th Street at 8:22 a.m. Monday, the NYPD said.

About two hours later, another man was fatally stabbed on East 30th Street, police said.

The third victim, a woman, is in critical condition after being attacked around 10:55 a.m. on East 46th Street, police said.

“He just walked up to them and started attacking them with the knives,” Detective Chief Constable Joe Kenny told a news conference.

The 51-year-old suspect — who lives at the Bellevue Men’s Shelter on East 30th Street — appeared to choose his victims at random, police said.

The suspect has eight prior arrests, according to law enforcement, and is believed to have serious mental health issues, Mayor Eric Adams said.

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

Two knives were recovered, police said.

“These random attacks left two innocent victims dead and another fighting for her life,” Kenny said. “We have one suspect in custody and are not looking for others at this time.”