UPDATE: Con Edison President Craig Ivey said the company sent a crew to 121 Second Ave. to check on a private contract company's work on a gas line one hour before the blaze expanded to four buildings. "The new installation did not pass inspection at time," Ivey said.
Mayor de Blasio confirmed to reporters the explosion appeared to be caused by plumbing and gas work inside 121 Second Ave.
The explosion caused a partial collapse inside the one building as a fire began to spread across four buildings, including 119, 121 and 125 Second Ave.
"Our thoughts and prayers are with everyone of them and their families," de Blasio said. "We are praying no other individuals are found injured and there are no fatalities."
There are no reports of additional missing people, de Blasio added.
FDNY Commissioner Daniel Nigro said critical injuries included burns to airways and one person who fell unconscious after the explosion.
Nigro also said the 7-alarm fire brought out 250 firefighters to the scene within less than 3 minutes.
There were no confirmed complaints about a gas leak before the explosion, but de Blasio warned all New Yorkers to still report any smells to 311 and Con Edison.
UPDATE: Twelve people are being treated by emergency responders, FDNY confirmed. Three are still critical.
Fire officials also confirmed that firefighters were working on the building at 121 Second Ave., which houses a Japanese restaurant on the first floor. NY1 reported the fire might have originated at the restaurant.
Mayor Bill de Blasio is expected to arrive at the scene for updates at around 5 p.
UPDATE: The FDNY confirmed with Metro that there are two buildings on fire.
The building at 125 Second Ave. is 7 stories tall. Building records also say it has 26 residential units, with clothing boutique Enz's on the first floor.
A Con Edison spokesman told Metro the company has a crew at the scene and began shutting down gas service in the area, although there is no confirmation that it was a gas explosion.
Police confirmed 6 injuries during the afternoon blast — three reportedly in critical condition, one in serious condition and two with minor injuries being treated at Bellevue and Beth Israel hospitals.
The Fire Department upgraded it to a 7-alarm fire by 4 p.m., one hour after officials said calls started coming in.
City records from the Department of Building show an open, but non-hazardous violation over noncompliance with regarding the building's facade dating to 2006. Previously resolved violations include objects, including flower pots, blocking the fire escape landing.
UPDATE: The Wall Street Journal reports that there have been at least four injuries in the explosion and subsequent building collapse in the East Village.
There are also reports of bodies lying on the ground. It is not known if there have been any fatalities.
Previously: A building collapsed and was engulfed in flames on Thursday in New York City's East Village neighborhood, authorities said.
There was no immediate information on possible injuries, said a spokesman for the New York Police Department.
Live footage on local television showed a residential apartment building engulfed in flames and heavy smoke.
Local television also reported a large explosion at the scene and an adjacent building also on fire.
Rescuers from the Fire Department of New York (FDNY) were headed to the location, which was on Second Avenue and East 7th Street in Manhattan, an FDNY spokeswoman said.
Reports of the collapse came in shortly after 3 p.m., she said.
Previously: A building has reportedly collapsed in New York City's East Village early Thursday afternoon.
It is not known if there are any inuries.
Stay with us for updates.