NYC building blast caught in dramatic video

Firefighters battle blaze at site of building collapse in New York City on March 26, 2015

REUTERS

Investigators believe a gas leak is the likely cause of a devastating explosion in New York City that destroyed three buildings and heavily damaged another.

Dramatic surveillance video captured the moment of the blast.

Nineteen people were hurt, four critically.

It sparked a seven-alarm fire that raged out of control.

Firefighters were still on-scene putting out hot spots Friday morning, reported CBS News correspondent Jericka Duncan.

Two people were unaccounted for, authorities said.

At least 250 firefighters worked to put out the raging fire, which sent a pillar of smoke hovering above the city.

In a matter of minutes one of the buildings came tumbling down on live television.

Witnesses reported hearing a loud boom shortly after 3:00 Thursday afternoon.

The powerful explosion blew the facade off one of the buildings.

Bystanders captured cell phone videos of people helping the injured to safety.

One woman was rescued by someone who climbed up a fire escape from the street below.

Soon after, several connected buildings were engulfed in flames.

New York Fire Department Commissioner Daniel Nigro said, "We have two people with burns to their airways and another person who had become unconscious following the event and was declared in critical condition."

Fire officials said at least two people were unaccounted for. Among them, is believed to be Nicholas Figueroa, 23. Members of his family said he was in a restaurant inside one of the buildings when the explosion happened.

College student Peter Manchini learned of the fire while watching the news at his school. He and his three roommates lived above the restaurant.

"All my belongings were in there, so just have to figure out, I guess, from there what's going to happen," he said.

City officials said private contractors were doing some gas and plumbing work in one of the destroyed buildings.

New York Mayor Bill de Blasio noted, "Con Ed inspectors arrived at the site earlier for a separate reason entirely, found the work to be unacceptable, gave instructions as to what changes were needed, and that was an hour or more before the explosion."

Some witnesses said they smelled gas at the time of the explosion but de Blasio said the city received no complaints. He stressed it is critically important that people call 911 or alert Con Edison immediately any time they smell gas.