Gas line explosions in three cities north of Boston killed one man and injured at least 20 others on Thursday afternoon, according to a Sept. 13 article from the New York Times

The explosions followed an announcement from Columbia Gas of Massachusetts earlier on Thursday that they would be upgrading natural gas lines across the state. The benefits of upgrading would include “enhanced safety features,” “reliability for years to come” and “less future maintenance work in your neighborhood,” according to the company’s website. As a result of the explosions, more than 8,600 homes and businesses were evacuated while inspectors determined whether it was safe to return, according to a Sept. 13 article in the New York Times

According to the Times article, shortly before 5 p.m. on Thursday, local officials responded to reports that residents were smelling gas and witnessing fires and explosions. As firefighters struggled to battle the fires, residents received contradictory orders about whether to stay or leave. By dusk, electrical power had been halted for more than 18,000 residents. Some towns experienced huge lines of traffic as locals fled their homes, not knowing when they would return.

At a press conference on Friday, Massachusetts Governor Charlie Baker declared a state of emergency and harshly criticized Columbia Gas for their delayed response. “Since yesterday, when we first got word of this incident, the least informed and the last to act have been Columbia Gas,” he was quoted as saying in a Sept. 14 Washington Post article.

On Saturday, Robert Sumwalt, a federal investigator, said there was “no evidence” that the explosions in Lawrence, Andover and North Andover, Massachusetts were planned, according to a Sept. 16 Associated Press brief. In a Sunday press conference, Sumwalt said the investigation will focus on the high pressure in the gas pipelines — the suspected cause of the explosions. Gov. Baker also announced Sunday that residents could return to their homes.