BOSTON (WHDH) - The Massachusetts State House will remain closed on Wednesday after a fire in a transformer room prompted an evacuation Tuesday afternoon, officials said.

Massachusetts State Police said the building was evacuated and nearly all surrounding streets on Beacon Hill were closed as crews responded to what appeared to be an electrical fire that broke out around 2:15 p.m. in a sub-basement at the capitol building.

In an update Tuesday evening, Superintendent of the State House Tammy Kraus said the building will be closed “Out of an abundance of caution while details of today’s fire continue to be investigated.”

“We’re grateful for the efforts of the Boston Fire Department, Mass State Police and DCR Rangers to ensure the safety of all officials, staff and visitors and are working diligently to reopen the building as quickly and safely as possible,” Kraus said.

Smoke was largely not visible outside the State House on Tuesday. Inside, though, state police spokesperson David Procopio said there were smoky conditions in parts of the building. As of 3 p.m., Procopio said firefighters were waiting for utility workers to cut power “before they make entry to extinguish the fire.”

Multiple Boston fire engines could be seen parked around the structure as authorities responded. Speaking with reporters, Boston Fire Department Commissioner Paul Burke said wires to a transformer caught fire, requiring utility crews to isolate the line and shut off power.

According to a staffer who spoke with 7NEWS, the afternoon evacuation was the second of the day after fire alarms went off earlier in the morning.

Personnel returned to the building after learning the first incident was an apparent false alarm, leading to some initially ignoring the second set of alarms.

“We had one earlier today and it was a fake alarm, so we were wondering if it was the same thing,” said staffer Adam Basile.

“It hard sometimes, when you’ve had a false alarm earlier in the day, folks think twice,” said state Senate Minority Leader Bruce Tarr. “They shouldn’t, but they take that extra minute to think ‘Is this real?’ They all need to be treated as real.”

Authorities said no injuries were reported and everyone was accounted for following the second evacuation.

Gov. Maura Healey was in the State House when the fire broke out. Like others, she was able to get out of the building safely.

Healey later addressed the situation in a Tweet, saying she is “grateful for the swift and coordinated action” from the Boston Fire Department, the Massachusetts State Police and the state Department of Conservation and Recreation rangers.

“Thank you for quickly evacuating the building and keeping officials, staff, and visitors safe,” Healey said.

Tarr also thanked first responders for their response.

“It’s not only serious because of public safety,” he said. “It’s serious because this is an historic building that has historic context.”

Officials said the fire posed problems for air quality inside the State House, with tests showing high levels of carbon monoxide.

As the emergency response continued, crews were at one point using fans to vent the building.

“They have readings,” Burke said. “An average reading of carbon monoxide might be 10, 11 parts per million. This was in the thousands, so it was not sustainable for a human.”

“It was a difficult fire to mitigate, so getting the smoke out of there and isolating the transformer feeds took a while,” Burke separately said. “But it’s done now. Everybody is safe.”

Roads in the area had reopened as of around 6:20 p.m., according to Procopio.

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