LOUISVILLE, Ky. (WDRB) -- Doss High School was placed on heightened security after an online threat Thursday.

A Jefferson County Public Schools spokesman responded to Doss. Doors at the schools were locked, and movement was restricted to only within the building.

A letter went home to parents of Doss students and parents of Trunnel Elementary, which is next door.

Doss High School is on St. Andrews Church Road in southwest Jefferson County, near Iroquois Park. 

The threat remains under investigation, but school returned to normal activity shortly after the initial response. No arrests have been made.

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