Two people remained missing on Friday as emergency workers began the delicate and complicated task of sifting through the debris of three buildings in the East Village that were destroyed the day before in an explosion and fire. 
 
 The fire on Thursday afternoon began with an explosion at 121 Second Avenue and grew to an inferno engulfing four neighboring buildings. At a news conference on Friday, Mayor Bill de Blasio said that while the investigation into the blast was in its early stages, “there is a possibility that the gas line was inappropriately accessed internally by people in the building.” 
 
 Small pockets of fire continued to smolder at the corner of Second Avenue and Seventh Street in the afternoon, as workers dug through the rubble with two giant cranes. A police officer lead a dog around the edges of the piles. 
 
 The sound of jackhammers, crane teeth on brick, and a police helicopter pounded the air. Water spilled from a broken pipe in a heap of debris, mattresses, picture frames, file cabinets and upholstered chairs. 
 
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 A “vibrant and bustling” street had been transformed, Mr. de Blasio said. 
 
 “You rarely see a scene of such devastation in the middle of a city like this,” he said. 
 
 City officials said the likelihood of finding survivors diminished with each hour. 
 
 One young man presumed missing, Nicholas Figueroa, was on a date at a sushi restaurant on the first floor of 121, according to his family. The second missing person was identified as Moises Ismael Locón Yac, 27, a busboy at the restaurant. 
 
 After the explosion ripped through the restaurant, Sushi Park, residents scrambled down fire escapes to safety, while others were helped down by bystanders. At a news conference on Friday morning, Police Commissioner William J. Bratton said the search was complicated, similar to what investigators faced after a gas explosion in East Harlem a year ago. 
 
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 Robert K. Boyce, the department’s chief of detectives, said that the police received initial reports of about 42 people who might be missing. But, the police concluded that only Mr. Figueroa and Mr. Locón were known to have been in the building at the time of the explosion. The authorities are still looking into reports of an additional missing person. 
 
 At least 22 people were injured, 18 with non-life threatening injuries, and four remained in critical condition, according to the authorities. Those with the most serious injuries, officials said, seemed to have been hurt during the initial blast. 
 
 The investigation into the explosion’s cause was focusing on plumbing and gas work being done at Sushi Park. 
 
 There was no current work permit on file for plumbing work to be done at that site, according to public records. 
 
 On Friday afternoon, officials said that workers from the utility Con Edison visited 121 Second Avenue at 2 p.m. on Thursday, leaving at 2:45 p.m. According to city officials, the owner of the restaurant smelled gas about 15 minutes later and called the building’s owner. After another 15 minutes, as workers were going to look in the basement, an explosion blew people out of the restaurant and onto the street. 
 
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 Diners had been taking advantage of half price deal of the day during Sushi Park’s lunch service. Survivors staggered in the dust and debris during the brief window after the explosion and before the fire, fueled by the gas that continued to leak from the basement, began to spread. 
 
 At least a dozen people escaped or were helped to safety. 
 
 Mike Shepherd, 47, a firefighter with Squad 41 based in the Bronx, was off duty, eating at a nearby restaurant. He ran to the scene. 
 
 “As I got closer to the corner I could feel the concussion bounced off the building across the street and kind of hit me in the chest and I said, ‘Oh man, it’s a big one.’ Then I looked and I turned and I see the whole building is out in the street and people laying there, and I said, ‘Oh man, this is bad.’ ” 
 
 He saw bodies sprawled on the ground; many of them looking cut and beat up, he said. 
 
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 They could not hear him, he said, and he waved to them with his hands. “How many missing?” he shouted. “How many at work today?” 
 
 Six, they answered; he counted only five people. 
 
 As firefighters converged on the scene, people on the street looked stunned. 
 
 “It was the loudest and most intense explosion I have ever heard,” said Tony Klinger, who had seen people in the restaurant just before the blast. “I thought it might be a bomb, some kind of terrorist attack. The whole inside of the storefront, of the restaurant, was outside on the sidewalk where I had just walked.” 
 
 Mr. Locón, described as earnest and hardworking, had been working in the main dining room of Sushi Park, one of 15 employees present. As his colleagues stumbled outside in the chaos after the explosion, they could not find him. They searched the hospitals and asked the police for help, but as of Friday afternoon had not gotten any news. 
 
 They feared the worst. 
 
 Mr. Figueroa, 23, had gone to Sushi Park for a lunchtime date. 
 
 His family has not heard from him since, they said. 
 
 His date, they said, was being treated for her injuries at Bellevue Hospital Center. She told her family that she and Mr. Figueroa were in the restaurant when it exploded. 
 
 “I don’t know what to do,” Mr. Figueroa’s brother Tyler, 19, said on Friday outside of a makeshift Red Cross center in the East Village. “We’re just praying that they find him.” 
 
 The family fanned out across Manhattan on Thursday afternoon to search for Nicholas. Tyler walked to a nearby hospital while his father, also named Nicholas Figueroa, and a cousin sought the help of the police. But there was no trace of him. 
 
 At the end of a long night of searching, his weary parents returned to their home on the Upper East Side, hopeful that he might have returned while they were away. 
 
 “My father is not stable, because he’s crying so much,” Tyler Figueroa said. “The police said that they’re looking into it, but we just want to know how this could’ve happened.” 
 
 The only thing the family knows for sure is that Nicholas had just paid his bill for lunch. 
 
 A bank statement, they said, shows a debit card transaction at Sushi Park for $13.04. ||||| Mr. Louire said he was told not to turn on a cellphone or anything else, and to leave the apartment and the building, at 1652 Park Avenue. He was in the lobby when he heard the explosion. 
 
 Elizabeth Matthews, a spokeswoman for the utility, confirmed that a customer at 1652 Park Avenue called to report a heavy gas odor at 9:13 a.m. Two minutes later, two Con Ed crews were dispatched, and they arrived just after the explosion. 
 
 The Fire Department said it received the first report of a fire at 9:31 a.m., and discovered on arriving two minutes later that the buildings had collapsed. There were a total of 15 apartments in the two buildings; one had a church on the ground floor, and the other had a piano store. 
 
 The buildings were five stories and about 55 feet tall, according to Buildings Department records. 
 
 The injured were taken to several area hospitals; most were treated and released. Officials said 13 people went to Harlem Hospital Center, including a 15-year-old boy in critical condition; 22 people at Mount Sinai Hospital, including a woman in critical condition with head trauma; and 18 at Metropolitan Hospital Center, all with minor injuries. 
 
 City officials urged families trying to find loved ones to call 311. Many congregated at a center set up by the Red Cross at a nearby school, even as they made appeals on social media for information about the missing. 
 
 About 250 firefighters from 44 units responded to the explosion. Heavy equipment was used to clear destroyed vehicles outside the buildings as firefighters started the painstaking task of searching the rubble brick by brick. By late afternoon, they could be seen sifting through the wreckage, passing buckets of debris hand to hand to clear it from the site. As night fell, there were still hot spots in the debris that limited rescue efforts.
– The death toll is climbing and hit seven this morning after authorities say a suspected gas leak blew up two apartment buildings in Harlem yesterday, just minutes after a customer called to report the smell of gas. At least 63 are wounded, and more deaths could come as two survivors suffered life-threatening injuries and another nine are still missing, CNN reports. As authorities continue to sift through the wreckage, the fire commissioner tell ABC News that rescue dogs have not detected the scent of any other victims. A Con Ed rep confirmed a customer call came in at 9:13am and crews responded two minutes later; they arrived just after the explosion, the New York Times reports. One man said the utility company told him to leave his building, and he was in the lobby when he heard the blast. Pianos flew through the air in a store on the ground floor of one of the buildings, WABC reports. "They flew off the ground and for me to get out I had to get around them," said a technician, who somehow escaped the building—which collapsed into a pile of rubble before the Fire Department arrived around 9:33am—with just scratches. Elsewhere, people were trapped in cars encased by debris. "It felt like an earthquake had rattled my whole building," said a man nearby. "There were glass shards everywhere on the ground, and all the stores had their windows blown out." Along with the piano store, the two buildings comprised 15 apartments and one church, the Times notes.