Investigators are trying to pinpoint the cause of a series of natural gas explosions that killed a US teenager and injured at least 10 others.
Authorities said an estimated 8,000 people had to leave their homes at the height of Thursday’s chaos in three towns north of Boston.
The National Transportation Safety Board was sending a team to investigate, saying pipelines are within its jurisdiction.
The rapid-fire series of gas explosions that one official described as “Armageddon” ignited fires in at least 39 homes in Lawrence, Andover and North Andover, forcing entire neighbourhoods to evacuate as fire crews scrambled to fight the flames and shut off gas and electricity.
Gas remained shut off on Friday in most of the area, and the streets were eerily deserted.
Authorities said Leonel Rondon, 18, of Lawrence, died after a chimney crashed into his car.
Massachusetts State Police urged all residents with homes serviced by Columbia Gas in the three communities to evacuate, snarling traffic and causing widespread confusion as residents and local officials struggled to understand what was happening.
Hundreds spent the night in shelters, and school was cancelled on Friday as families waited to return to their homes.
“It looked like Armageddon, it really did,” Andover fire chief Michael Mansfield said. “There were billows of smoke coming from Lawrence behind me. I could see pillars of smoke in front of me from the town of Andover.”
Governor Charlie Baker said state and local authorities were investigating but that it could take days or weeks before they turn up answers.
Te utility company issued a statement saying its crews need to visit each of the 8,600 affected customers to shut off each gas meter and conduct a safety inspection.
“We expect this will be an extended restoration effort, and we will work tirelessly to restore service to the affected customers,” the statement said.
The Massachusetts Emergency Management Agency blamed the fires on gas pipes that had become over-pressurised but said investigators were still examining what happened.
Columbia had announced earlier on Thursday that it would be upgrading gas pipes in neighbourhoods across the state, including the area where the explosions happened. It was not clear whether work was happening there on Thursday.