Explosion in Manhattan Apartment Building

b_250_0_16777215_00_images_obgrabber_2014-03_fb87e19976.jpgWABC NY (NEW YORK) --Two people were killed and at least 28 injured Wednesday when a suspected gas explosion tore through a building in Manhattan's East Harlem neighborhood, collapsing at least part of the structure, authorities said. “This is a tragedy of the worst kind because there was no indication in time to save people,” New York City Mayor Bill de Blasio said in a news conference Wednesday. “There will be a search through the rubble of the building once the fire has been put out.”

"They were right there," one source told ABC News, referring to the explosion. Another victim is in very serious condition, the source said.

In addition to the two dead, both women, two people had life-threatening injuries, two more had serious but not life-threatening injuries and the others had minor injuries, the Fire Department said. De Blasio noted that several people were still unaccounted for.

A New York City official said the casualty "numbers are going to change."

Plumes of thick smoke have engulfed the area around the building at 116th Street and Park Avenue after residents reported hearing a loud explosion around 9:30 a.m. and the smell of smoke was overpowering. The first 911 call came in at 9:31 a.m. and firefighters were on the scene two minutes later, Fire Commissioner Sal Cassano said.

Con Edison was responding to a report of a gas odor at 1652 Park Ave., officials said. The call came in at 9:13 a.m. from a resident of that building who indicated the odor may have been coming from outside the building. Two Con Edison crews were dispatched at 9:15 a.m., officials said, noting they arrived just after the explosion occurred. The street is served by an 8-inch low-pressure gas main, utility officials said. There were a total of 15 residential units in the two buildings, officials said.

There is "no indications of foul play,” de Blasio said.

The FBI was on the scene as a precautionary measure, but there is no indication of terror or crime, authorities said.

Google images of the building show two commercial storefronts on the ground floor with residential apartments above those storefronts.

Shattered windows in nearby shopfronts show the extent of the explosion, which may have been caused by a gas leak, according to ABC station WABC.

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SLIDESHOW: See photos from the scene of the explosion

“We are expending every effort to locate each and every loved one," de Blasio said.

There are more than 250 firefighters working at the scene, as well as dozens of pieces of equipment to clear the rubble.

Any relatives who are looking for info about their loved ones can call 311 until a special hotline is set up, officials said.

Residents in the area are posting pictures of the building on social media.

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