Police believe the threat was fake, but Westchester County's Bomb Squad was sweeping the high school at 300 Hornidge Road, Mamaroneck, for any hazards.
Sgt. Sandra DiRuzza, a spokeswoman for the Village of Mamaroneck Police Department, said, "A student at the school sent an email to another student stating he was going to plant a bomb at the school."
"The student was identified and questioned about the email threat. The threat appears to have no merit,'' Sgt. DiRuzza said. "The school was evacuated and the Westchester County Bomb squad conducted a sweep of the school as a precaution."
The sweep was completed and students are being allowed back onto the school grounds, DiRuzza said just before noon on Tuesday.
The Village of Mamaroneck Fire Department responded, staging its fire trucks along Boston Post Road. Earlier, detectives reportedly detained one student for questioning.
An investigation was continuing, police said, and no one was reported hurt as a result of the hour-long evacuation.
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