Two killed and one critically hurt in New York knife attacks

Two people have died and a third person was critically injured after a man went on a stabbing spree across Manhattan on Monday, police said.

New York police say they arrested the 51-year-old suspect following the "unprovoked" knife attacks at three different locations.

The two men who died were taken to an area hospital before they were pronounced dead. The third victim, a woman, was stabbed near the United Nations headquarters and she remains in critical condition, authorities said.

The attacker is a homeless man who had recently been sentenced in a criminal case, New York City Mayor Eric Adams told reporters.

"Three New Yorkers. Unprovoked attacks that left us searching for answers on how something like this could happen," Adams said at a news conference.

The mayor said the violence was "a clear, clear example" of failures in the criminal justice system.

He said the suspect has "severe mental health issues" that need examination and there are questions about why he was out on the streets.

The motive for the stabbings is unclear.

"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 said .

The NYPD have posted the pictures of two knives they say were recovered at the site of the stabbings.

The first man killed was a 26-year-old construction worker standing near his work site at the time of the attack, Mr Kenny said.

The second man killed was a 68-year-old who was fishing in the East River when he was attacked.

A third stabbing occurred nearly two hours later when a 36-year-old woman was stabbed multiple times outside the UN headquarters, police said.

A taxi driver saw the woman get attacked and notified police which led to the suspect's arrest.

None of the three victims have been named by the police.