Hazmat police fear there's been an attempted mass suicide in New York City involving unknown chemicals.

The New York Fire Department responded to an emergency "chemical-related" call-out at an address in Queens at about 6:30am on Thursday morning.

Officers from the 105th Precinct had initially responded to the location after receiving a 911 call about an emotionally disturbed person at an address on Hampstead Avenue.

There they found a 30-year-old man who was acting erratically, AMNY reports.

The officers then entered the home where they discovered an unconscious 72-year-old man with "trauma to his body" who was pronounced dead at the scene.

Hazmat police attended the scene on Hampstead Avenue, Queens
Hazmat police attended the scene on Hampstead Avenue, Queens

The nature of his injuries have not yet been specified.

Police officers also reportedly found a 70-year-old woman, a 31-year-old man and a 29-year-old woman who were all unconscious and unresponsive inside the residence.

The three unconscious people were then rushed to Long Island Jewish Medical Centre in critical condition, according to reports.

The nature of their injuries is unknown at this time, law enforcement sources told media.

The 30-year-old man was then taken into custody and is now being evaluated, police reported.

Officers say the area has now been made safe and there is no danger to other residents of the building.

The situation is currently still developing, with a large group of police officers spotted at the scene still.

A stretcher has also been seen outside the building along with a fire truck and ambulance both parked nearby.

No further details about the fatal incident or the toxic substances involved have been released by police yet.

The incident is not believe to be terror-related.

For emotional support, you can call the Samaritans 24-hour helpline on 116 123, email [email protected], visit a Samaritans branch in person or go to the Samaritans website.