At least one person has been killed and many others injured after a series of reported gas explosions rocked towns north of Boston in Massachusetts.
Local police reported "fires and explosions" at dozens of homes and other properties on Thursday evening.
Hundreds of people were evacuated, with gas and electricity services cut to try and prevent further incidents.
A local fire chief described it as an "overwhelming event" that resembled "Armageddon".
"I have been in the fire service for almost 39 years and I have never seen anything like this in my entire career," Andover Fire Rescue Chief Michael Mansfield said.
Leonel Rondon, 18, was killed inside a car in the town of Lawrence when a chimney fell on his vehicle from a house explosion, a spokeswoman with the Essex County District Attorney's office said.
Family members told local media that he had been in the car with two friends, who were now in hospital.
Officials say at least 25 people have been treated for injuries, but it is not clear how severe a condition they are in.
Mr Mansfield said investigators suspected the fires were caused by "over-pressurisation of a gas main" belonging to Columbia Gas lines.
How did events unfold?
Officials said that between 60 and 80 fires and a number of explosions broke out in homes and businesses in the towns of Lawrence, Andover and North Andover, which are located around 30 miles (45km) north of Boston.
Witness accounts suggest the incidents began at about 16:30 local time (20:30 GMT).
Fire crews then spent hours going from property to property tackling blazes, as gas technicians rushed to shut off gas supplies and assist in safety checks.
Residents were also urged to cut off their gas supplies if they could do so safely, and advised to evacuate.
Neighbouring police chief Joseph Solomon, who came in to assist from the town of Methuen, said there were so many fires burning at one point that you could not see the sky.
Shelters were later set up in schools, churches and other properties while roads leading into the areas affected were closed.
In the early hours of Friday the Governor of Massachusetts, Charlie Baker, described the incident as a "public safety event", but said officials were now "confident" there would be no further fires.
He later said that it had been an "incredibly difficult day".
The gas firm's parent company, Indiana-based NiSource, earlier said its thoughts were with those affected.
"The first priority for our crews at the scene is to ensure the safety of our customers and the community by supporting first responders and completing safety checks on our system and in the surrounding area," it said in a statement.
What is the situation now?
Lawrence Mayor Dan Rivera has asked some South Lawrence residents to stay away from their homes until further notice - even if they do not have Columbia Gas.
"There could still be a gas leak in your home," he said. "You can't see it and in some cases you won't be able to smell it, and God forbid you go to sleep and don't wake up."
He described the community as "very resilient" but warned people to make alternative arrangements until they are told it is safe to return.
Residents in North Andover who were evacuated were told to "expect that the restoration process will take several days - or longer," by the town manager, Andrew Maylor.
He said that a number of North Andover streets had been "cleared to return", but advised residents not to switch on their gas supplies. "Call Columbia Gas to do that," he said in a tweet.
Almost 18,000 customers had been left without power because of the emergency switch-offs, according to the Massachusetts Emergency Management Agency.
The incident is being investigated by the FBI, the State Fire Marshal's Office and the National Transportation Safety Board, local media report.