HINGHAM (CBS) — Hingham High School was temporarily in lockdown mode Monday morning after the school received a threatening phone call. All of the students are safe, Hingham Police said.

The lockdown ended around 11:15 a.m. and a regular school schedule has resumed.

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A “reported threat” is being investigated by police. No word yet on whether police believe the threat is credible or not.

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“Several police units are present at the school,” police tweeted during the lockdown. Following the lockdown’s conclusion, police said some officers would remain at the school.

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Principal Rick Swanson emailed Hingham High parents about the lockdown. “After we received a phone call about an alleged threat, we immediately contacted local police and placed the school in a lockdown,” he said.