Rocky Hill Superintendent of Schools Mark Zito announced the security measure in an email to parents, NBC Connecticut reported.
Zito did not relay what the message said but explained that an unauthorized user had accessed an account and posted the threat in a Google Doc. The school system's IT department quickly removed the message and is now investigating how the system was breached, the report continued.
Police said the threat was not specific and the lockdown is a security protocol. Officers are investigating who made the post.
The lockdown only impacted Rocky Hill High School.
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