Updated story: An investigation is underway after Hardin Valley Academy dismisses students early after a gas valve in a science lab was left running overnight.

The Knox County Sheriff’s Office investigated a tip and found that a contract custodian intentionally left the gas valve running.

Officials with Knox County Schools say the employee was arrested and immediately fired by his employer.

Knox County Sheriff Tom Spangler says after this week’s events in Nashville, they and KCS take any threat seriously. (rj)

Original story: Hardin Valley Academy has dismissed students early after a gas valve in a science lab was left running overnight, causing disruptions to learning.

Knox County Schools says the air was tested and no trace of gas was detected.

Due to the smell, the school is still dismissing.

Students officially left at 1 p.m.