The high school in Weston, Connecticut, was evacuated and placed on lockdown on Wednesday due to an "unconfirmed threat," authorities for the suburban town said.
The threat was under investigation by the school administration and Weston police, said Weston Communications Center Director John Ojarovsky.
"There was an unconfirmed threat," he said. "As a precaution, the high school was locked down."
About 800 students attend the public high school in Weston, located about 20 miles south of Newtown, Connecticut, where 20 children and six adults were killed in a gunman's massacre at an elementary school in December.
The lockdown at Weston High School took place at 12:30 p.m., Ojarovsky said. There were no further details immediately available about the nature of the threat, he said.
Weston, an affluent town in southwestern Connecticut that is home to such celebrities as Rolling Stones' guitarist Keith Richards, is about 50 miles northeast of New York City.
A spokeswoman for the Weston Police Department said its chief would have a statement later in the afternoon.
(Reporting by Ellen Wulfhorst; editing by Andrew Hay)