A major explosion following a gas leak has reduced two residential buildings in New York to rubble, killing two women and injuring 22 people.
New York Mayor Bill de Blasio described the incident as a tragedy of the worst kind, saying a number of people were still unaccounted for as firefighters battled to extinguish the blaze in East Harlem.
"There was a major explosion that destroyed two buildings. The explosion was based on a gas leak," he said.
The mayor said there were 15 apartments in the two buildings that collapsed at 116th Street and Park Avenue.
So far the only indication as to the cause of the blast was a call from an adjoining apartment building at 9.13am local time alerting energy company Con Edison to the smell of gas, AFP reports.
The explosion came barely 15 minutes later, sparking a major fire and engulfing the area in a column of dense white smoke. The New York Fire Department got an emergency call at 9.31am, and firefighters were on the scene two minutes later.
Train services in and out of Grand Central Station in midtown Manhattan were suspended as a result of the incident next to its tracks.
Witnesses said they were jolted awake by what sounded like an earthquake. Robert Santiago told CBS that he was sleeping when all of a suddenly the explosion shook his bed and the floor. "I thought the world was coming to an end, an earthquake or something like that. Terrible," he said.
Authorities in the area were said to be handing out medical masks to residents due to the thick white smoke at the scene.
Hundreds of police and more than 250 firefighters were on site with emergency trucks, as a dense column of smoke poured into the sky over the Metro-North railway line.