"When the explosion occurred, I understand a couple of the PSE&G guys got knocked off their feet, but they were OK, and everybody else was alright as far as fire people," said Chief Norman Jensen, of the Edison Fire Department.
Fortunately, no one was injured.
Fire and gas crews have been securing the site in Edison for more than nine hours.
They are working underground to shut down a huge gas main that, so far, appears to be the problem.
"When you look down at it, it's cracked around the circumference. Why, I couldn't tell you. At this time of year, you have a lot of movement of the ground when it freezes, and then it just thaws out," explained Chief Jensen.
While 60 homes in the area were immediately evacuated as a precaution Monday morning, most people have been allowed to return home.
Homes in the immediate area remain evacuated and a nine-block stretch of Route 27 remains closed.
"They are currently working on the cracked gas main which is located right in the middle of Route 27, as soon as they can secure that, we will be allowing more of the evacuees to return to their homes and businesses," said Sgt. Robert Dudash, of the Edison Township Police Department.