A natural gas explosion that injured 18 people and damaged 42 buildings has been blamed on a utility worker who accidentally punctured a high-pressure pipeline while looking for a leak.
State fire marshal Stephen Coan said Friday night's blast in the entertainment district of Springfield, Massachusetts, one of the largest cities in the north-eastern New England states, was caused by "human error".
He did not name the Columbia Gas worker who pierced the pipe while responding to reports of a leak.
The worker damaged the underground pipe while using a metal probe to locate the source of the leak, Mr Coan said. A flood of gas then built up in a building that housed a strip club, and a spark touched off the blast, officials said.
Mr Coan said the employee was following older markings on a pavement that indicated the location of the gas line. He appeared to be an appropriate distance from the line, but the markings were incorrect and he accidentally punctured the pipe.
Columbia Gas, a subsidiary of public company NiSource, said on Sunday that it planned to open a claims centre at City Hall for residents and businesses affected by the explosion.
Preliminary reports showed the blast damaged 42 buildings with 115 residential units. Three buildings were immediately condemned and 24 others require additional inspections by structural engineers to determine whether they are safe. The building that housed the Scores Gentleman's Club was destroyed and a children's day care centre next door heavily damaged.
After the pipe was ruptured, authorities evacuated several buildings. Most of the people injured were part of a group of gas workers, firefighters and police officers who dived for cover behind a utility truck just before the blast. The truck was demolished.
Some officials said it was a miracle no one was killed. Springfield fire commissioner Joseph Conant praised the actions of city firefighters.
"The firefighters did an excellent job evacuating the area which certainly prevented additional civilian injuries and saved many lives," Mr Conant said.