SPRINGFIELD, Mass. (AP) -- Dozens of building inspectors began assessing homes and businesses in one of New England's biggest cities on Saturday, a day after a natural gas explosion leveled a strip club located next to a day care and heavily damaged a dozen other structures. The blast injured 18 people, many of them first responders.
Investigators were trying to figure out what caused the Friday night blast in Springfield that could be heard for miles, left a large hole in the ground where the multistory brick building housing Scores Gentleman's Club once stood and scattered debris over several blocks.
Officials had already evacuated part of the entertainment district after responding to a gas leak and odor reported about an hour before the explosion while firefighters, police officers and gas company workers were in the area filled with commercial properties and residences.
"It really is a miracle and it's an example of our public safety officials, each and every day, putting themselves in harm's way, taking what could have been considered a very routine call of an odor of gas, but they took the proper precautions," State Fire Marshal Stephen Coan said. "And thanks to God that they did."
Officials also marveled how the 5:30 p.m. blast occurred when a day care center next door was closed. The center's building was heavily damaged.
Lt. Gov. Tim Murray and Springfield Mayor Domenic Sarno were attending a tree-lighting ceremony when the explosion occurred. Sarno said some people mistakenly thought the boom was part of the holiday event.
The explosion blew out windows in a three-block radius, leaving at least three buildings irreparably damaged and causing emergency workers to evacuate a six-story apartment building that was buckling, police said. Pieces of broken glass littered streets and sidewalks. It was unclear how many residents had been evacuated. A shelter was set up at a school.
Omar Fermin, manager of the Punta Cana Restaurant two blocks from the explosion site, found the floor-to-ceiling windows blasted out when he came to check on the property Saturday morning.
"It looks like an earthquake hit," said Fermin, a native of the Dominican Republic. "I've never seen anything like it."
He said he was waiting for somebody to come and assess the damage. He worried the restaurant would remain closed for weeks while the owner seeks to replace the massive custom-made windows.
Authorities cordoned off the center of the explosion Saturday morning as building inspectors worked to identify unsafe structures. Anxious residents gathered at the perimeter, waiting for permission to visit their buildings.
Dogs trapped in abandoned buildings barked out loudly Saturday as building inspectors fanned out across the area. One inspector said he wished he could get a ladder and permission to retrieve a dog that was barking in the upper floor of one building sealed off from residents.
Coan, the fire marshal, said his office was investigating a cause of the blast and its possible origin. The state's Department of Public Utilities was also investigating.
Sheila Doiron, a spokeswoman for Columbia Gas of Massachusetts, said the company will continue to monitor for any potential leaks within several blocks of the blast site. So far, she said, the company hadn't yet found any measurable readings.
Doiron said the company also didn't find in its records any gas odor calls to the area where the strip club was located.
The victims were taken to two hospitals in the city. None of their injuries was considered life-threatening, officials said. Those injured were nine firefighters, two police officers, four Columbia Gas workers, two civilians and another city employee.
Springfield, which is 90 miles west of Boston and has about 150,000 residents, is the largest city in western Massachusetts. It's known as the home of the Basketball Hall of Fame, which is not in the vicinity of the blast.
The city has been rebuilding from damage it sustained in a June 2011 tornado.
On Friday night, residents milled around the neighborhood where the explosion occurred, stunned by the destruction and confused by the cordoned-off area, which grew as crews continued to search for gas leaks. The mayor warned against looting, saying police would be out in force.
Wayne Davis, who lives about a block away from the destroyed building, said he felt his apartment shake.
"I was laying down in bed, and I started feeling the building shaking and creaking," he said.
The Navy veteran said the boom from the explosion was louder than anything he'd ever heard, including the sound of a jet landing on an aircraft carrier.
The blast was so loud it was heard in several neighboring communities. Video from WWLP-TV showed the moment of the explosion, with smoke billowing into the air above the neighborhood.
Associated Press writers Rodrique Ngowi, Bridget Murphy and Bob Salsberg in Boston and Jessica Hill in Springfield contributed to this report.