A building has collapsed in New York after an explosion killing at least six people and leaving more than 20 people wounded.

The blast happened around 9.00 am local time (2.00 pm CET) in East Harlem at a residential building on Park Avenue between 114th and 117th streets.

Debris was thrown hundreds of feet and cars crushed.

The New York Fire Department is dealing with the blaze and heavy smoke rising from the scene.

The bomb squad also responded as a precaution.

Officials suspended train services in and out of Grand Central Terminal as the building is close to the Metro-North railway tracks.

It is unclear what caused the explosion although there are unconfirmed reports of a gas leak.

Now: Photo of #Manhattan collapse. #FDNY has 39 units and 168 members responding. The scene is developing. pic.twitter.com/zWhTmi9Dsm — FDNY (@FDNY) 12 Mars 2014

RIGHT NOW: Live video feed of explosion/collapsed building in Harlem, NYC. http://t.co/Dm3qwgsj5Npic.twitter.com/6TpdPKFgtz — Jim Roberts (@nycjim) March 12, 2014

Huge explosion at east harlem. A building just completely exploded. pic.twitter.com/0sBuG5U0d0 — Adnan Islam (@orangeadnan) 12 Mars 2014