SOUTH MILWAUKEE, Wis. (CBS 58) -- South Milwaukee High School and Middle School are on a secure hold Tuesday morning, Sept. 14, after authorities received a report of a threat.

A letter sent to parents and guardians said the South Milwaukee High School administration became aware of the vague threat as students were arriving at school.

The South Milwaukee Police Department is investigating the threat. Currently, the South Milwaukee High School and Middle School are on a secure hold with students being kept in their classrooms during the investigation.

More information will be released as it becomes available.