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.
Associated Press writers Bridget Murphy and Bob Salsberg in Boston contributed to this story.