Cambridge

Multiple manhole explosions in Cambridge's Harvard Square forced evacuations, closures

When firefighters arrived they spent the first 45 minutes evacuating businesses due to dangerously high carbon monoxide levels

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A manhole explosion in Cambridge's Harvard Square on Wednesday morning caused major traffic disruptions, according to police.

Cambridge police said the manhole explosion was reported around 8:30 a.m. in the vicinity of 27 Brattle Street. Firefighters were working to extinguish a fire following the explosion, and Eversource is also at the scene.

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Fire officials said Wednesday afternoon that there were two separate manhole explosions, and a third one that was actively smoking. When firefighters arrived they spent the first 45 minutes evacuating businesses due to dangerously high carbon monoxide levels.

“We had very high CO readings, well over 100, at a number of the businesses in this area," Acting Fire Chief Thomas F. Cahill Jr. told reporters, adding that anything above 0 is of concern, and they begin evacuations at 35 parts per million (ppm).

The fire chief said they continue to detect high levels of carbon monoxide as they try to contain the fires from the manholes in Harvard Square.

One firefighter was transported with life-threatening injuries during the response, Cahill said. Crews are still actively working to contain the fires and gas.

"It’s not separate businesses with their own buildings so it’s challenging when you get into these basements and you identify the high levels of this dangerous gas,” adding that it’s dangerous for firefighters even with their personal protective equipment.

Harvard Square is closed to vehicle traffic as a result of the explosion and subsequent response, and pedestrian traffic is restricted. Businesses along the stretch will remain closed at least for the evening because of the CO. There is no timeline for when things may reopen.

“I’m not sure if these businesses will be open tomorrow, they certainly won’t be open tonight," Cahill said.

He said the cause of the explosions is not yet clear and the situation is still active.

Police said people should avoid traveling through Harvard Square until further notice if at all possible.

First responders at the scene of a manhole explosion that closed down Harvard Square in Cambridge, Massachusetts, on Wednesday, Aug. 30, 2023.
Cambridge Police Department
First responders at the scene of a manhole explosion that closed down Harvard Square in Cambridge, Massachusetts, on Wednesday, Aug. 30, 2023.

The incident happened on an especially busy day in Harvard Square, as Wednesday is move-in day for incoming first-year students at Harvard University.

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