A knife-wielding assailant killed two men and critically wounded a woman during an hourslong, seemingly "unprovoked" stabbing spree through the streets of New York City on Monday, authorities said.

The two slain men — attacked near 444 W. 19th St. at 8:22 a.m. ET and then by 500 E. 30th St. at 10:27 a.m. — were taken to Bellevue Hospital before they were pronounced dead, officials said.

Then a woman was stabbed in the shadow of the United Nations, near East 42nd Street and First Avenue at 10:55 a.m., leaving her in critical condition.

A "person of interest" was captured a short time later at 46th Street and First Avenue, said police, who are not searching for anyone else in connection to these stabbings.

“As of right now, these attacks seem to be unprovoked, that he just walked up to them and began to attack them with the knives,” NYPD Chief of Detectives Joseph Kenny told reporters.

The suspect in custody was not named, but police described him as a 51-year-old homeless man with a recent arrest record.

"We are still looking over his record, but there's a real question on why he was out on the street," Mayor Eric Adans said.

“He was sentenced a few months ago and there’s a real question that we need to look at on why he was out on the streets, and he has some severe mental health issues that should have been examined.”

An officer caught up with the alleged assailant after a taxi driver saw the woman attacked, officials said, believing he was witnessing a robbery, and called police.

The victims were not immediately identified, pending notification of their families.

The first man killed, who was 36 years old, was attacked at a construction site where he was working, police said.

The second victim was 68 years old and was fishing at the end of 30th Street when he was attacked, authorities said.

“I want to thank the everyday New Yorker who notified (arresting NYPD) officer (Robert) Garvey and told him what he observed," Mayor Adams said.

"When he saw the assault, he followed the individual involved and gave the information to officer Garvey, who took quick action and was able to apprehend the person who we believe is a suspect."

The attacks come as violent crime is a major topic in both New York and national politics, though the actual incidents of such felonies appear to be declining.