Utility workers accessed 8,600 meters, turned them off and cleared each home of gas in Lawrence, Andover and North Andover as of 6:30 a.m. Sunday, the governor said.
Investigators suspected the fires were caused by "over-pressurisation of a gas main" belonging to Columbia Gas lines.
Thousands had evacuated after a series of violent explosions Thursday afternoon.
"It looked like Armageddon, it really did", said Andover Fire Rescue Chief Michael B. Mansfield.
The blasts were likely caused by over-pressurized gas lines to individual residents, Andover Police Department Lt. Eddie Guy told NBC's Today television show Friday morning.
"We are very interested to understand the operations of Columbia Gas". They say their system is up to date, modern and created to ensure that when gas flows into a customer's home, it's flowing at the appropriate pressure. "We will be looking at their record keeping, their procedural compliance, their procedures, their training, the oversight of their contractors", Sumwalt said Saturday.
Officials said gas company technicians will turn all the meters back after safety inspections of the entire system are complete - a process expected to take several weeks.
"Our mission is to find out what happened so we can keep it from happening again", Sumwalt said. Leonel Rondon, 18, died after a chimney fell on his auto in Lawrence. Residents should contact authorities if they smell gas, or notice fire-related damage or anything odd with their gas appliances, he said.
"This is a good example of someone coming home, as we've asked, finding something wrong, and telling us right away", Moriarty said.
"It's going to be a complicated process to get you back to normalcy", Lawrence Mayor Dan Rivera said.
Utility President Steve Bryant later defended the company's performance, saying the company had remained in constant touch with state and federal officials.