New York City Buildings Collapsed, 4 Killed

Firefighters respond to a fire on 116th Street in Harlem after a building exploded in huge flames and billowing black smoke, March 12, 2014, in New York. (AP Photo/John Minchillo)

Two New York City apartment buildings on a largely residential Upper Manhattan block at East 116th Street and Park Avenue collapsed in a massive explosion on Wednesday at about 9:30 a.m. (1330 GMT).

Firefighters work the scene of an explosion that leveled two apartment buildings in the East Harlem neighborhood of New York, March 12, 2014. (AP Photo/Jeremy Sailing)

At least four people were killed and at least thirty others were injured, while more than a dozen people are reportedly missing.

Officials feared more victims are trapped in the rubble and they are searching for them.

This undated file photo shows two buildings (center) on 116th St. and Park Ave in East Harlem, that are the subject of building collapse in NYC on March 12, 2014. (Via Google Maps)

Reuters reported that there were a total of 15 apartments in the five-story buildings.

Gas leak is believed to be the caused of explosion.

Please click here for more photos:

Emergency workers respond to the scene of an explosion and building collapse in the East Harlem neighborhood of New York, March 12, 2014. (AP Photo/Jeremy Sailing)

Firefighters respond to a fire on 116th Street in Harlem after a building exploded in huge flames, March 12, 2014, in New York. (AP Photo/John Minchillo)

Firefighters try to extinguish a fire as smoke bellows from the site of a building collapse in Harlem, New York in this picture provided by Adnan Islam March 12, 2014. (REUTERS/Adnan Islam/Handout via Reuters)

Firefighters try to extinguish a fire as smoke bellows from the site of a building collapse in Harlem, New York in this picture provided by Adnan Islam March 12, 2014. (REUTERS/Adnan Islam/Handout via Reuters)

New York City firefighters hose down the rubble from a building that collapsed on Park Ave. and 116th Street in New York, March 12, 2014. (Gordon Donovan/Yahoo News)

Downtown Philadelphia Building Collapse Killing 6, Injuring 14

Screen shot from ABC channel 6 in Philadelphia showing the before and after of the collapsed building.

A four-story empty building at 22nd and Market streets in the heart of Philadelphia’s busy Center City district collapsed in downtown Philadelphia burying a neighboring thrift shop in concrete and debris at around 10:45 a.m. EDT, Wednesday June 5, 2013.

The collapsed building was under demolition when it suddenly fell down on the thrift shop.

At least one man and five women were killed while fourteen others were injured in the disaster.

It was reported that those who were killed were inside the Salvation Army thrift store.

At a late night news conference Mayor Michael Nutter said:

“We still do not know how many people were inside the thrift store or possibly on the sidewalk. If someone else is in that building, they will find them.”

Authorities say the cause of the sudden collapse was still under investigation.

Please click the photos for larger images:

JUNE 5: Rescue workers search for victims and clear debris from a building that collapsed in an apparent accident at a demolition site, at 22nd and Market Streets, June 5, 2013 in Philadelphia, Pennsylvania. The building being demolished landed on top of a Salvation Army Thrift Store, destroying most of it and reportedly trapping and injuring over a dozen people. (Photo by Jessica Kourkounis/Getty Images)

Rescue personnel work the scene of a building collapse in downtown Philadelphia, Wednesday, June 5, 2013. A four-story building being demolished collapsed Wednesday on the edge of downtown, injuring 12 people and trapping two others, the fire commissioner said. Rescue crews were trying to extricate the two people who were trapped, and the dozen people who were injured were taken to hospitals with minor injuries, according to city Fire Commissioner Lloyd Ayers. (AP Photo/Jacqueline Larma)

Emergency personnel respond to a building collapse in downtown Philadelphia, where the city fire commissioner says as many as eight to 10 people are believed trapped in the rubble, Wednesday, June 5, 2013. (AP Photo/Dino Hazell)

Screen shot from ABC channel 6 in Philadelphia showing the before and after of the collapsed building.

Constructions workers help to clean the debris following a building collapse in Philadelphia June 5, 2013. REUTERS/Eduardo Munoz

Firefighters search through rubble following a building collapse in Philadelphia June 5, 2013. A building collapsed in downtown Philadelphia on Wednesday, killing a 35-year-old woman and injuring 13 other people under mountains of crushed concrete and splintered wood, officials said. REUTERS/Eduardo Munoz

Firefighters block the view while they search through rubble for a body following a building collapse in Philadelphia June 5, 2013. A building collapsed in downtown Philadelphia on Wednesday, killing a 35-year-old woman and injuring 13 other people under in mountains of crushed concrete and splintered wood, officials said. REUTERS/Eduardo Munoz

Firefighters and rescue workers search through rubble following a building collapse in Philadelphia June 5, 2013. A building collapsed in downtown Philadelphia on Wednesday and rescue workers pulled 12 people from the rubble and were trying to reach two others trapped beneath it, fire officials said. REUTERS/Eduardo Munoz

In this photo provided by Jordan McLaughlin, a dust cloud rises as people run from the scene of a building collapse on the edge of downtown Philadelphia on Wednesday, June 5, 2013. A building that was being torn down collapsed with a thunderous boom, raining bricks on a neighboring thrift store, killing a woman and injuring at least 13 other people in an accident that witnesses said was bound to happen. (AP Photo/Jordan McLaughlin)