Police rerouted traffic around the intersection of River Street and Memorial Drive after shots were fired at approximately 1:30 p.m. on Monday. At least a dozen marked and unmarked State Police vehicles responded, and Boston Police closed off access to Cambridge from Storrow Drive and the Mass Pike.

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Several ambulances also responded. It was unclear whether anyone had been shot. The Cambridge Police Department put out a citywide alert at 2:04 p.m. saying the scene was an active police scene but there was not an on-going danger to the public.

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Cambridge Police did not respond immediately to requests for more information. Traffic was still being re-routed as of 2:15 p.m.

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Cambridge Day will update this story as more information is available.