Two women have died after an explosion in an apartment building that then collapsed in East Harlem, New York City, BBC reports citing police sources.
Seventeen others were injured in the incident, which sent smoke billowing into the city sky.
Residents heard a blast in the five-storey building at 116th Street and Park Avenue before it caved in.
All train services in and out of Grand Central terminal have been halted following the incident near its tracks.
The New York fire department has elevated the incident to the highest threat level possible.
It announced it has dispatched 198 members from more than three dozen nearby fire stations to battle the blaze.
A utility company says a resident in a nearby building reported smelling gas shortly before the explosion on Wednesday morning.
Streets and pavements around the site were littered with broken glass from shattered windows.
Witnesses reported the powerful blast knocked items off shelves in nearby stores.
Authorities in the area were said to be handing out medical masks to residents due to the thick white smoke at the scene.
A witness told the BBC “there was just a lot of panic” following the explosion.
an Scarvino had just emerged on to a nearby train platform when “suddenly a plume of smoke came out of nowhere”.
“I’ve never seen anything like it,” he added.
A witness told the New York Daily News 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 the newspaper he heard two loud explosions that shook the barber shop where he works.
“It was loud, like boom, boom!” Mitch Abreu said. “It rocked the whole block.
“A window blew out of the other shop down the street,” he added.
“It looked like the [Twin] Towers all over again. People covered in dust and covering their mouths.”