Updated at 1:30 a.m. on Friday, Sept. 14

Massachusetts State Police have confirmed 70 fires, explosions and reports of gas odor in Lawrence, Andover and North Andover, all stemming from a gas leak Thursday afternoon. Roughly 25 people were injured, and one person — 18-year-old Leonel Rondon — was killed when a chimney fell on his car following an explosion.

Multiple officials — from Gov. Charlie Baker to the Andover fire chief and the North Andover town manager — said it was not clear when people would be able to return to their homes but cautioned that it could be days. Roughly 146,000 people live in the three communities affected by the incident.

The fires appeared to be largely under control, but technicians from Columbia Gas along with firefighters and police are going building to building to shut off the gas and inspect 8,000 meters. State and local officials urged patience with the process, which they expect to stretch well into Friday if not beyond.

Baker said that he had spoken with the president of Columbia Gas and stressed that "they must immediately bring in additional resources" and have a comprehensive plan to make sure homes are safe. While the focus remains on public safety for now, those responsible for the crisis will be held accountable, he added.

The National Transportation Safety Board — the federal agency that oversees investigations involving accidents in civil aviation, rail and highway travel, and pipelines — announced it was sending a "go-team" team to Lawrence to investigate the incident. Joining the NTSB will be the Department of Transportation pipeline safety team and the Massachusetts Department of Public Utilities.

Lawrence General Hospital has seen 13 patients from the incident, one in critical condition, one in serious condition. Cases at the hospital range from smoke inhalation to traumatic blast injuries. One patient has been transported to a Boston-area hospital. In total, about 25 people were treated for injuries, some of whom have already been released.

Columbia Gas issued a statement around 9:30pm, telling customers not to turn off gas to their house or any appliances. The company also advised people not to light matches or candles, or to use cell phones, lights, appliances or power tools that could cause a spark.

At a press conference earlier in the day, Andover Fire Chief Michael Mansfield said the city experienced 38 fires, and the fire department responded to 17 additional gas leaks.

Mansfield, who has served for nearly 39 years, said he’s never seen anything like this.

“To sum it up, basically coming into town ... it looked like Armageddon. It really did,” he said. “There were billows of smoke coming from Lawrence behind me. I could see plumes of smoke in front of me within the town of Andover. It just looked like an absolute war zone. [It’s] something that I’ve never experienced in my fire service career, and hopefully I don’t have to experience it ever again.”

Although Mansfield said many of the fires were minor, that didn’t mean they were easy to handle.

“We had companies out there that were responding to a building fire, they would extinguish the building fire, they would come outside and they’d find the next building next door on fire as well,” he said. “So quite a different experience than we’re used to and something that we’ll be analyzing and looking at all the data for a long time.”

Certain Andover residents were cleared to head home Thursday evening. Those who live south of the intersection of Rt. 28 and Salem Street and those who live west of the intersection Beacon Street and Reservation Road were told they could return to their houses. Residents north of Rt. 28 at Salem Street were urged to find alternative accommodations. In Lawrence, residents in the southern part of the city were told to evacuate.

Jay Hudak from Andover described a scene of people panicking to turn off their gas meters. “There ... was a guy that is a semi-plumber, and he couldn't force it because he said he was so afraid … that he [might] break something off. ... You'd have a broken pipe. So he left them all."

Hudak also expressed concern that the gas meters are outside.

“I'm kind of upset that these meters that have been put outside for eight to 10 years," he added. "In this kind of emergency when they're telling us to turn them off individually that they've rusted and we can't turn them off. I mean that's kind of negligent on their part.”

Lawrence Mayor Dan Rivera said city officials are working with state police to ensure that the streets of Lawrence remain safe in the blackout. He also stressed that people need to be patient with the process and not rush home.

Public schools in Lawrence, Andover and North Andover will be closed Friday, according to district websites and Twitter feeds.

Police closed all off-ramps on I-495 from exits 41 through 45. The on-ramps remained open throughout the evening to allow residents to evacuate.

Columbia Gas of Massachusetts, which serves over 300,000 customers and has three service areas in the state, had announced on its website Thursday that it would be “upgrading natural gas lines in neighborhoods across the state,” to provide “enhanced safety features” as well as more reliable service. It was not immediately clear whether that work had any connection to the fires. (The company is one of seven utilities around the country owned by Indiana-based NiSource.)

National Grid has also cut electric power to almost 18,000 customers in the area. A spokesperson for the company told WGBH news, that "was as requested by local authorities and there is no estimate for restoration at this time."

Lawrence City Councilor Marc Laplante represents the southside of the city where most of the explosions occurred. He says there were two fires in his neighborhoods that have been extinguished.

“I don't think I'm going home tonight. I’m going to have to find someplace else to sleep,” LaPlante said. “I have three kids and a wife. I doubt we're going to be allowed to go back into our homes.”

The city is directing residents to the Arlington Middle School and Parthum Middle School if they need shelter. They can call 211 for more information.

Laplante cautioned that residents be calm and not panic.

“We need the gas company to find a solution and find out what’s going on and get answers and a solution quickly," he said. "We’re a big city.”

This story is developing.