KNOXVILLE, Tenn. (WATE) — Knox County Schools has announced they will conduct an internal review after two gas valves left on in a high school science lab led to the evacuation of the school and the arrest of a custodian.

According to Knox County Schools Superintendent Jon Rysewyk, the Asst. Superintendent of Business and Talent Jennifer Hemmelgarm will conduct a formal review of the incident.

The main focuses in the review are “the actions taken by the school and district leaders in response to the incident” and “the protocols and procedures in place to address similar situations should arrive again.”

Last week, the Knox County Sheriff’s Office arrested 23-year-old Jay Kostermans after an investigation found that he left a gas valve on overnight in one of the science labs at Hardin Valley Academy.

The school was required to dismiss early.

According to court records, investigators believe he turned on two natural gas valves in a chemistry lab prior to leaving for the evening out of anger over a dispute with a family member.

Kostermans was terminated by his employer, which is listed as Duncan and Sons Building Maintenance in court records. The business was contracted by the school district earlier this year to address a custodial staffing shortage at several schools.

A preliminary hearing has been set for April 27.