A powerful explosion tore the roof off a pharmaceutical plant in Massachusetts early Thursday, injuring multiple workers and leaving one unaccounted for, fire officials said.
Acting Fire Chief Stephen Bradbury III said the plant suffered "significant structural damage," preventing firefighters and rescue crews from entering the building.
The explosion happened around 1 a.m. at the Sequens/PCI Synthesis plant. Video footage showed most of the roof torn off a building. The blast blew a vat from the building 30 feet into a parking lot, Bradbury said.
Five workers were in the building at the time of the explosion. Four workers were taken to a local hospital where they were treated and released. A fifth remains unaccounted for as of Thursday afternoon.
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Authorities said there was no threat to the local population or to homes near the Newburyport building, but fire officials told employees who work in the industrial park where the facility lies to stay away.
It wasn't immediately known what caused the explosion, or if any chemicals were involved. It was also unclear what role the vat may have played in the explosion.
"All our attention is focused on the situation of our employees," PCI Synthesis said in a statement.
Fox News Digital has reached out to the company for updates.
Fire crews were meeting with a demolition company, the city's structural engineer and a building inspector "to make sure it's safe for us to continue our search," he said.
Chemists from the company and a technical rescue crew have responded. A spokesperson for the federal Occupational Safety and Health Administration said that agency was also involved.
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In 2020, authorities said a chemical reaction caused a series of explosions at the plant. That happened a year after OSHA found "serious" violations in how the company managed highly hazardous chemicals, according to online agency records. There were no serious injuries cited in those events.
A chemical fire in the building in June 2021 sent smoke pouring out of roof vents and prompted a hazardous materials team to respond. Sprinklers controlled the fire within about 20 minutes, but the city suspended the factory's permits during the investigation.
The factory has also been cited by OSHA for workplace safety violations and in 2019 paid a more than $50,000 penalty to settle Environmental Protection Agency charges that it violated hazardous waste laws.
The Associated Press contributed to this report.
