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, before the explosions and fires.
The explosions killed Leonel Rondon, 18, while he sat in a auto in the driveway of a home in Lawrence, authorities said.
MBTA buses are being used to drive people to their homes.
Residents in communities north of Boston that were rocked by natural gas explosions were given the green light Sunday to return to their homes.
Gas service to all homes in the affected area has been shut of and the homes cleared of gas as of 6:30 this morning, according to public safety officials.
"We still have a very long way to go, but we're very happy that people can return to their homes this morning", Baker said.
The National Transportation Safety Board is still investigating the cause of the MA explosions.
"The evacuations are in the thousands", Hall said Friday, adding he expects many residents were staying with friends and family in the surrounding area. Hundreds of natural gas technicians were to descend on the towns in the coming days to restore gas service safely before electricity could be turned on, state officials said. Leonel Rondon, 18, died after a chimney fell on his vehicle in Lawrence.
NiSource was working with investigators and taking "full responsibility" for the findings of the safety board's investigation, the company's chief executive, Joe Hamrock, said at a news conference Sunday.
Massachusetts Gov. Charlie Baker declared a state of emergency Friday in the three towns and put another utility company in charge of restoration efforts. The company a subsidiary of NiSource, a utility company that serves more than three million customers in seven states.
Columbia Gas of MA, which provides service in the affected communities, declined to comment on Sunday on what caused the leaks, saying federal investigators would decide.