CHICAGO (CBS) — A northwest Indiana high school was placed on lockdown after vague telephone threat on Wednesday.

Police immediately searched Munster High School and found the threat to be unfounded.

Students were in summer school and members of the local swim club were also attending practice.

Officials said the Lake County 911 center received an anonymous call that referenced Munster High School and the pool. According to a release from Munster police, the caller stated “that there was a person in the school/pool area planning to do harm.”

In an email to parents, school administrators said: “The Munster police department responded immediately and performed a thorough search of Munster High School. After the search, the lockdown ended and summer school is operating as normal.”

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