Maine public safety officials and natural gas companies said they will be reviewing safety measures in the wake of the series of explosions in Massachusetts that destroyed dozens of homes, killed one person and injured at least 25 others on Thursday.

Early indications are that the lines were over-pressurized, forcing gas into homes and other businesses, where it ignited explosively. Maine’s natural gas system has never experienced a similar problem, officials said, although explosions have occurred in individual homes and buildings when gas lines failed.

“In my whole career, I’ve never seen anything like this,” Portland Fire Chief Keith Gautreau said. He said the only similar case he could think of occurred more than five years ago, when a propane leak in Yarmouth killed one man and destroyed a condominium unit and damaged another.

The explosions Thursday afternoon occurred in Andover, North Andover and Lawrence, Massachusetts, causing fires in more than 60 homes. A teenager was killed while sitting in a car outside one of those homes when a chimney toppled onto the vehicle. Authorities are still investigating the cause of the explosions.

Natural gas in Maine is delivered by companies that are not affiliated with Columbia Gas, the company that serves those three towns and others in Massachusetts. The company had announced earlier Thursday that it would be upgrading delivery lines in parts of Massachusetts, including the Andover-Lawrence area where the explosions occurred.

The Massachusetts gas pipeline system is among the oldest in the country, as much as 157 years old in some places, The Associated Press reported, citing the Conservation Law Foundation, an environmental advocacy group.

Unitil, which provides natural gas to southwestern Maine, including Portland, said the company intends to perform a review of its systems once the cause of the Massachusetts explosions has been determined. Once that investigation concludes, Gautreau said the fire department will contact Unitil to see if they need to coordinate on updating safety drills to prevent something similar from happening in Portland.

Unitil has a series of checks in its system to detect over-pressurization, said Alec O’Meara, a spokesman for the utility.

He said two gas line regulator devices are designed to sound an alarm if the system is over-pressurized. In addition, utility employees monitor pressure in the system around the clock and a third regulator has been installed at some points where the system delivers the gas to a home or business, O’Meara said.

That third regulator is a newer feature, he said, and has been installed during more recent connections. O’Meara said he didn’t have figures on how many customers have the third regulator.

The system worked about four years ago, when it detected over-pressurization in part of Unitil’s system, O’Meara said. The first regulator failed, but the second caught the problem and employees were able to step in and prevent any danger or interruption in service, he said.

But, he said, that situation did not come close to causing the kind of catastrophe that hit the three towns in Massachusetts.

“Nothing like this has happened in our system,” he said.

Maine officials also said they know of no similar problem in the state.

Summit Natural Gas, which provides service from Falmouth to Madison, said it was sending technicians to help out in the Merrimack Valley towns hit by the explosions.

Lizzy Reinholt, senior director of corporate affairs at Summit, noted that federal officials have begun an investigation of the explosions as recovery efforts continue.

She said it would be “premature” to comment on possible causes.

A spokesman for Maine Natural Gas, which serves Windham, Gorham, Bowdoin, Topsham, Brunswick and Freeport, also said his company won’t comment until an investigation of the explosions in Massachusetts is complete.

FREQUENT CALLS

Firefighters in Portland respond to natural gas problems almost weekly, Gautreau said. Often, he said, construction crews will hit a gas line while working on a building and less often, a resident will report a gas odor because a pilot light has failed, allowing gas to seep into an apartment or office.

Reports of natural gas leaks “are always challenging calls to go on and you have to slow down and take your time and trust your equipment,” he said.

Firefighters have portable monitors that sniff the air for flammable gases, he said, and the devices alert them if a high reading is detected.

Natural gas fires are almost impossible to put out unless service is cut off, Gautreau said. The companies add a chemical to natural gas, which is colorless and odorless, that makes it smell like rotten eggs. The odor is very strong so people will know if the gas is present, but it’s hard to detect the specific source of the leak by the intensity of the odor, he said.

From a firefighting perspective, “it’s almost better if the house is on fire” because firefighters can pinpoint the problem, he said.

Indoor leaks are more dangerous than outdoor ones, where the lighter-than-air gas is easily dispersed, he said.

The safety of natural gas systems in Maine is overseen by the Maine Public Utilities Commission, which has three full-time inspectors and an administrative employee decided to gas safety.

Those inspectors monitor 1,210 miles of natural gas distribution main lines, 84 miles of intrastate transmission lines and set standards for about 700 propane gas distribution sites, according to the PUC’s annual report.

Maine State Fire Marshal Joe Thomas said his agency is not responsible for natural gas safety, but he did call the fire marshal in Massachusetts to offer the state’s help. He said officials in Massachusetts said they had called in crews from elsewhere in their state, along with New Hampshire, and extinguished the fires Thursday night.

Thomas said New England fire marshals are likely to discuss the incident when they hold their next quarterly meeting in Massachusetts.