A gas explosion has levelled two buildings and sparked a fire in New York City, killing at least two people and injuring 18 others.
One five-storey building appeared to be reduced to rubble, and a second severely damaged near Park Avenue and 116th Street in East Harlem.
New York Mayor Bill de Blasio said "a number of people are missing" and a search effort will begin after firefighters put out the blaze.
He emphasised that some of those considered missing could be in another location and authorities are attempting to make contact with all concerned.
"This will take quite a bit of time to address" Mr. de Blasio said.
Witnesses reported hearing a large explosion around 9am.
Aerial footage showed a large plume of smoke billowing over the Upper Manhattan skyline and debris scattered across the pavement and vehicles parked on adjacent streets.
Eoin Hayes (26) lives on the 23rd floor of a nearby building and feared the worst.
Smoke is seen rising from the building (Image via @Eoin_Hayes on Twitter)
Witnesses say the blast was so powerful it knocked groceries off the shelves of nearby stores.
The FDNY says it has over 200 personnel at the scene. The cause of the explosion was not immediately known.
Local electric and gas companies were shutting down service in the area.
Metro-North Railroad has suspended all commuter train service in the area. The train line runs along the scene of the collapse, and television footage showed some debris on the tracks.
The White House says President Barack Obama was briefed on the incident, and that he will continue to be updated as new information becomes available.
"Our thoughts and prayers go out to everyone impacted by this incident and commend the first responders working tirelessly to save lives and contain the fire" it said in a statement.
This man says the smoke from the collapse could be seen for miles around.
