It is now safe for thousands of Massachusetts residents to return to their homes, the authorities said, three days after gas leaks triggered a series of startling explosions and fires that killed one and injured more than 20 others.
Thousands had been evacuated after a series of violent explosions on Thursday afternoon. Governor Charlie Baker of Massachusetts twittered On Sunday, the police, fire brigade and supply squads had "safely cleared" thousands of homes in Andover, North Andover and Lawrence.
However, authorities have not explained exactly what caused the explosions, and a Massachusetts Emergency Management Agency spokesman did not answer questions on Sunday. The National Transportation Safety Board is investigating, but did not return requests for comment on Sunday.
The gas lines of Columbia Gas of Massachusetts were the focus of the investigators. Authorities have previously said that they are considering the possibility that the gas may have been put under pressure that was too high for the pipelines it crossed.
The announcement on Sunday follows the completion of what the authorities call phase 1 of the response to the explosions – clearing gas leaks and restoring power to these homes.
In the next phase, the authorities will investigate the damage to the gas system and thereafter "any device from the meter where gas enters a building to equipment in a building that distributes gas to all devices," Mr Baker said on Twitter.
The explosions killed Leonel Rondon, 18, while sitting in a car in the driveway of a house in Lawrence, the authorities said. A chimney fell on the car, they said as the house on Chickering Road exploded.