Firefighters, police officers and gas company workers in the area because of an earlier gas leak and odor report were among the 18 people injured in the blast, authorities said.
"This is a miracle on Worthington Street that no one was killed," Lt. Gov. Tim Murray said at a press conference.
The explosion in Springfield, 90 miles west of Boston, blew out all windows in a three-block radius, leaving three buildings irreparably damaged and prompting emergency workers to evacuate a six-story apartment building that was buckling, police said.
Police Sgt. John Delaney marveled at the destruction at the blast's epicenter, where a multistory building housing a Scores Gentleman's Club, evacuated earlier because of the gas leak, was leveled.
"It looks like there was a missile strike here," he said.
The victims were taken to two hospitals in the city. None of their injuries was considered life-threatening, officials said. Those hurt were nine firefighters, two police officers, four Columbia Gas of Massachusetts workers, two civilians and another city employee.
Firefighters responded to the scene at 4:20 p.m. and were investigating the gas leak when the blast happened about one hour later. The cause of the explosion hadn't been identified but was under investigation, they said.
Springfield, which 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.
The explosion happened in an area of downtown Springfield with commercial properties and residences. Area resident Wayne Davis, who lives about a block away from the destroyed strip club 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 for miles around. Video from WWLP-TV showed the moment of the explosion, with smoke billowing into the air above the neighborhood.
Mayor Domenic Sarno said it was through "God's mercy" that nobody had been reported killed in the explosion.
"My thoughts and prayers are with the individuals that have been injured and the people who have been displaced," he said, adding that emergency shelter was being set up for those unable to go home.
An official of the gas company said there were no signs of any additional gas leaks in the area but crews would be monitoring the area closely over the next two days.