Firefighters on Friday used high-powered water towers to extinguish pockets of fire at the site of an apparent gas explosion in Manhattan's trendy East Village as authorities reported that two people were still unaccounted for.

Nineteen people were injured, four critically, after the powerful blast and fire sent flames soaring and debris flying Thursday afternoon. Authorities said they were searching for Nicholas Figueroa, who had been on date at the Sushi Park restaurant, and Moises Lucon, a worker there.

Preliminary evidence suggested that a gas explosion amid plumbing and gas work inside the building was to blame. An hour before the blast, utility company inspectors decided the work being done there was faulty.

The explosion caused the collapse of three five-story buildings and damage to a fourth, which was seven stories tall, the Fire Department of New York said.

On Friday, firefighters poured gallons of water over the wreckage, a giant wave of crumbled brick, twisted metal and splintered wood. That morning was the first chance for many neighbors to see the damage up close.

Naomi Machado, who has lived in the East Village neighborhood for 35 years, was in tears as she glanced at the rubble on her way to work.

"I'm totally devastated," she said. "For my neighbors, for our neighborhood. We all look out for one another."

Naho Ikechia, 36, was shocked by the scene — and grateful the damage wasn't even greater.

"If it would have been at night, when the restaurants are full and people are home from work, it would have been so much worse," she said. "This is such a busy area."

Initial evidence pointed to a gas explosion. A plumber was doing work connected to a gas service upgrade in one of the now-destroyed buildings, and inspectors for utility company Con Edison had been there earlier Thursday, company President Craig Ivey said. But the work failed the inspection, partly because a space for the new meters wasn't big enough, Con Ed said.

A woman listed in city records as the building's managing agent didn't immediately respond to messages Friday. An engineering firm involved in getting permits for work at the building declined to comment.

A contractor who was injured in the blast — and who's facing unrelated charges of bribing an undercover investigator posing as a housing inspector — declined through his lawyer to comment on the circumstances surrounding the explosion. City records show the contractor, Dilber Kukic, got a permit last June for plumbing, flooring, removing partition walls and other work at the building.

Police Chief of Detectives Robert Boyce said Kukic had tried to help people escape the explosion and had been helpful to authorities.

Kukic was treated and released from a hospital, said his lawyer, Mark Bederow.

"His thoughts are with the people who are injured and the victims of this," Bederow said Friday.

Kukic is a relatively minor player in a 50-person bribery case that Manhattan District Attorney Cyrus R. Vance Jr. and other authorities unveiled last month. They said city inspectors, landlords and contractors formed a network of graft that exchanged $450,000 in payoffs to get safety violations dismissed, procure phony eviction orders and get fast, favorable and sometimes nonexistent inspections.

Kukic is accused of paying $600 in cash to try to get housing violations dismissed at two upper Manhattan properties he owned. He has pleaded not guilty.

On Thursday night, Tyler Figueroa said his 23-year-old brother, Nicholas, had disappeared after going on a date at the East Village sushi restaurant, where the facade was still intact Friday.

Figueroa said that the couple was paying for their meal when the blast occurred and that his date, who is in the hospital, remembers only stumbling outside before losing consciousness.

"I just pray my brother shows up," he said. "We just hope my brother comes back."

Diners ran out of their shoes and bystanders helped one another escape the blast, which sent flames shooting into the air, witnesses said. Passers-by were hit by debris and flying glass, and bloodied victims were aided as they sat on sidewalks and lay on the ground.

The blast happened a little over a year after a gas explosion in a building in East Harlem killed eight people and injured about 50. A National Transportation Safety Board report released last week said a leak reported just before the blast may have come from a 3-year-old section of plastic pipe rather than a 127-year-old cast-iron segment that came under scrutiny immediately afterward.

Mayor Bill de Blasio noted that no one had reported a gas leak before Thursday's blast. Con Edison said it had surveyed the gas mains on the block Wednesday and found no leaks.

Bystander Blake Farber, who lives around the corner, said he'd been walking by the building and smelled gas seconds before the big blast.

The explosion was so forceful it blew the door off a cafe across an avenue and left piles of rubble on the sidewalk. One witness said his son helped to lift debris off a man so he could escape the restaurant where they had been eating.

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Associated Press writers Jennifer Peltz, Verena Dobnik, Tom Hays, Jonathan Lemire, Mike Balsamo, Kiley Armstrong and Stephanie Siek contributed to this report.