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.

“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.