An explosion has destroyed two New York City apartment buildings, killing at least two people and injuring 17 others.
The fire department said more than a dozen people were missing and that two of those injured have life-threatening injuries.
A utility company says a resident in a nearby building in East Harlem reported smelling gas shortly before the explosion, though the cause of the blast is as yet undetermined. The odour was believed to have been coming from outside.
The company sent two crews to investigate, but they arrived just after the explosion.
The explosion centred on a five-storey building near Park Avenue and 116th Street, and it sent huge flames and billowing black smoke into the air.
Pavements in a large surrounding area were littered with broken glass from shattered windows.
Witnesses said the blast was so powerful it knocked food off the shelves of nearby shops.
Police, some wearing gas masks, handed out medical masks to residents and onlookers because of the thick smoke that shrouded the area.
Eoin Hayes, 26, said the explosion shook his entire apartment building in Harlem at about 9.30am local time. He ran to the window and saw flames consuming one building and smoke rising into the air.
“I was in my bedroom and the explosion went off, it kind of shook the whole building,” he said. “You could feel the vibrations going through the building.”
The explosion occurred close to elevated Metro-North commuter train tracks. Metro-North services were suspended to and from Grand Central on all three train lines while employees removed debris from the tracks.
The fire department said it sent nearly 170 members to the scene.
New York City mayor Bill de Blasio visited the scene, and in a statement afterwards he confirmed a “number” of people were missing following the explosion. The people who died were both women.
Meanwhile, a spokesman for utility firm Con Edison said it is working with the fire department “checking gas lines”.
He added: “We’re working to isolate any leaks and make the area safe.”
Waldemar Infante, 24, a porter from a nearby residential building who was working in the basement when the explosion occurred, said: “It felt like an earthquake had rattled my whole building.
“There were glass shards everywhere on the ground and all the stores had their windows blown out.”
Mr de Blasio added that some of those unaccounted for may have fled to safety, but the city will make every effort to location everyone.
One witness claimed she had smelled gas “for weeks” before the explosion.
“We saw people flying out of the window... those are my neighbours,” Ashley Rivera said.
Another witness told reporters he heard two loud explosions that shook the barber shop where he works. Mitch Abreu said: “It looked like the [Twin] Towers all over again. People covered in dust and covering their mouths.”