A woman in a New York apartment building was ambushed in a lift by her deranged ex-lover who torched her with a Molotov cocktail, also known as gasoline bomb.

Deloris Gillespie, 64, burned to death in the lift as the man fled the building, while neighbours who were unaware of her plight called the fire brigade, the Daily Express reported Monday.

The gruesome attack was carried out as Gillespie returned home from shopping.

Two CCTV cameras, including one inside the lift, recorded the one minute-long assault in Brooklyn, a borough.

The man was waiting for Gillespie when the lift doors opened to the fifth floor of the six-storey building. Equipped with a canister containing flammable liquid connected to a nozzle, he stepped into the lift and sprayed his victim in the face and body.

CCTV footage shows the attacker wearing what look like white surgical gloves and a protective mask.

New York police said a man had walked into a police station early Sunday morning smelling of petrol and claiming to be the killer.