An underground explosion in downtown Boston sent two utility workers to the hospital and caused a major rescue response down the street from the state capitol Tuesday, fire officials said.
The transformer explosion occurred while the Eversource workers were performing routine maintenance in an underground electrical vault, fire officials said. The workers were injured but able to get out of the vault under their own power.
Witnesses described hearing a loud boom and seeing smoke and fire. One woman said she heard a worker scream.
Eversource confirmed two workers were sent to the hospital in the incident, which fire officials said would be investigated by OSHA as an industrial accident.
Get New England news, weather forecasts and entertainment stories to your inbox. Sign up for NECN newsletters.
"At this time, our focus is on our employees’ well-being and making sure they receive the medical treatment and support they need," Eversource said in a statement, noting that the investigation into exactly what happened is ongoing.
The explosion at Bowdoin Street near Cambridge Street was reported just before 6 p.m., Boston fire officials said. The two injured workers were taken to Massachusetts General Hospital.
Fire crews worked with Eversource to cut the power and put out a fire associated with the explosion.
A witness said he heard the explosion from his bedroom.
"I’m sitting on my bed and I look out my window and I see the manhole cover on fire, and all of a sudden I heard pop pop pop boom, louder than anything," he told NBC10 Boston.
Another man said after he heard the noise he looked outside and saw a man's clothing falling off of him.
The initial reports came through as a manhole explosion, prompting officials to ask the public to avoid the area over concerns there would be more. However, fire officials later said the explosion was caused by the transformer. They were investigating what happened.
Images from the scene showed a large fire rescue response blocking the road near Bowdoin and Cambridge streets.
The city has seen several issues with manholes in recent months. Earlier Tuesday, Boston firefighters briefly shut down Congress Street after smoke came billowing out of a manhole cover at the corner of Quaker Lane.
In June, a woman was injured when two manhole covers blew off on High Street as a result of an over-pressurization underground. And back in May, fire burst from two other manholes on Boylston Street, causing smaller explosions but no injuries.
