Kadena Middle School on Kadena Air Base, Okinawa, is part of the Department of Defense Education Activity. (Keishi Koja/Stars and Stripes)

Students at a Defense Department middle school on Okinawa were released two hours after the school day began on Tuesday due to a cooling problem.

Kadena Middle School on Kadena Air Base sent students home at 9:30 a.m. due to an electrical issue affecting the building’s air conditioning system, the school announced on its Facebook page.

Buses departed at 9:45 a.m., according to the post. Staff were to remain at the school until all students had been picked up.

Temperatures reached 88 degrees Fahrenheit by 9:30 a.m. and were expected to reach 91 degrees. Humidity pushed the real-feel temperature past 100 degrees, according to accuweather.com.

Parents were notified of the early release through Department of Defense Education Activity’s online student information system portal, DODEA-Pacific spokeswoman Miranda Ferguson said by phone Tuesday.

The school’s administration discovered the problem after arriving at school and immediately notified American Engineering Corp., Ferguson said in a follow-up email. She had no further information about the electrical problem or its cause.

The company is “on site supporting maintenance staff and working diligently to address the electrical issue; however, we currently do not have an estimated time of completion,” according to the Facebook post.

Parents will be notified Tuesday evening about school operations Wednesday, the post said.