Springfield residents displaced by a natural gas explosion on Nov. 23 are slowly returning to their homes.

The blast injured more than 20 people and damaged 42 buildings, according to reports from the AP.

Springfield building commissioner Steve Desilets was at home at the time of the blast.

“I heard a big boom – it actually shook my house,” said Desilets, who lives about 11 miles from where the gas line exploded. “Within a few minutes, my phone started ringing off the hook.”

Officials from Columbia Gas said one of their employees, who was responding to reports of a gas odor, accidentally damaged an underground pipe while searching for a leak. The employee, who Columbia Gas officials said was practicing correct protocol, was following a system of markers on a sidewalk that were incorrect.

State officials are now investigating why the markings were inaccurate, and whether there is a potential greater problem.   

There were no fatalities in the explosion, which Desilets said is the result of fast response time from police, firefighters and Columbia Gas.

“What we wanted to do [was] make sure that we provided immediate assistance and be on site immediately so that people could talk to someone face-to-face,” Sheila Dorin, director of communications for Columbia Gas, said.

Meanwhile, this incident has raised concerns about the state of Boston’s gas utilities.

Nathan Phillips, lead researcher of Boston University’s study on the city’s gas leaks, said last year that such leaks could “contribute to global warming” and “create explosions in some cases."