Dogs trapped in abandoned buildings barked 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.
Authorities are opening an animal shelter for pets affected by the explosion, Walsh said.
Coan, the fire marshal, said his office is investigating the 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.
The utility will keep at least 30 workers at the scene, along with a so-called sniffing car mounted with sophisticated gadgets capable of detecting low levels of gas leaks, Walsh said.
Doiron said the company also didn't find in its records any gas odor calls to the area where the strip club was located.
Authorities also deployed police officers throughout the area to prevent looting, Walsh said.
The victims were taken to two hospitals in the city. 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 near the blast site.
The city has been rebuilding from damage caused by a tornado in June 2011.
Wayne Davis, who lives about a block 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.