At least six people have died and several are missing after a gas leak sparked an explosion which levelled two buildings in New York City.
Scores of others were injured in the incident, which sent smoke billowing into the city sky.
Rescue crews began searching the debris on Wednesday evening for victims after the fire was finally put out.
Train services to and from Grand Central Terminal have been restored after a complete halt earlier.
As the search-and-rescue operation continued under floodlights on Wednesday night, the emergency services confirmed that the death toll had risen first to four, then to five and to six, with several people still missing.
Earlier, New York City Mayor Bill de Blasio said in a news conference from the scene that the gas leak had been reported to the utility company 15 minutes before the blast on Wednesday morning.
Mr de Blasio said the "major explosion" had destroyed two buildings and heavily damaged other structures.
As night fell, rescue crews were finally able to search for victims in the debris after the fire raged for most of the day.
Heavy equipment, including a bulldozer, helped clear the remnants of two multi-storey buildings. Thermal imaging cameras were brought in to identify bodies or pockets of fire inside the mountain of debris.
The New York fire department said 22 people had been hurt, but a tally of local hospitals by ABC News found that 64 had been admitted with injuries as a result of the incident.
That figure included seven children, one of whom was in a critical condition.
The utility company, Con Edison, says a resident in a nearby building reported smelling gas shortly before the explosion.
Streets and pavements around the site were littered with broken glass from shattered windows.
The blast scattered debris across nearby rooftops, correspondents say, destroying adjoining five-storey buildings in a largely Latino working-class neighbourhood.
Witnesses reported the powerful blast knocked items off shelves in nearby shops.
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.
Dan 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."
"It looked like the [Twin] Towers all over again. People covered in dust and covering their mouths."