Official: Sensors are a focus of gas blast probe

LAWRENCE, Mass.—The investigation into the Boston-area natural gas explosions is partially focused on pressure sensors that were connected to a gas line that was being taken out of service shortly before the blasts, the head of the National Transportation Safety Board said Sunday.

NTSB Chairman Robert Sumwalt said the sensors can signal for gas pressure to be increased if the pressure gets too low. He said investigators will try to determine whether those sensors played any role in Thursday’s explosions and fires.

Dozens of homes were destroyed or damaged, a teenager was killed and dozens of people were injured in Lawrence, North Andover and Andover. Thousands were forced to leave their homes.

Also Sunday, residents in the three communities north of Boston were allowed to return to their homes after crews finished shutting off nearly 8,600 gas meters. Electricity was restored to all the affected homes and businesses, but gas service may not be restored for weeks.

“It’s evident to me and to all of us the Merrimack Valley and the residents of our state are being as supportive as they can be and as kind as they can be to one another during this most difficult time,” Gov. Charlie Baker said at a news conference Sunday.

Schools in Lawrence will be closed today because of the natural gas situation, officials said.

Sumwalt said the investigation is focused on high pressure in pipelines. On Saturday, he said officials will be looking at how local Columbia Gas officials responded to a “pressure increase” in the Lawrence area that was detected at the company’s pipeline control center in Columbus, Ohio, prior to the explosions and fires.

He said there was no evidence the explosions were intentional.