NASHVILLE (AP) - Tennessee Department of Correction Commissioner Derrick Schofield assured lawmakers that the state's prisons are safe despite staff vacancies and recent violence at two of its prisons.

Schofield's appearance before the House State Government Committee on Monday comes amid the department switching correctional officers from a traditional 40-hour work week to a 28-day schedule to save $1.4 million in overtime costs.

Critics say the change has caused staffers to leave, which has impacted prison safety. Last month, eight prisoners were injured in stabbings at the Northwest Correctional Complex in Tiptonville, and the Northeast Correctional Complex in Mountain City was placed on lockdown after a July 19 incident that injured an officer.

Schofield acknowledged that vacancies do exist, but he said he doesn't believe the schedule change is a factor. He says some staffers simply left for private employment. However, he said sa fety can be maintained with current staffing levels.