A battery explosion that seriously injured one employee at General Motors’ Warren Tech Center is being blamed on the extreme testing of an experimental battery. The explosion occurred at about 8:45am this morning.According to GM, the explosion was related to “extreme testing on a prototype battery.” GM says the lithium-ion battery that was involved is not related to the Chevrolet Volt or any other production vehicle. At least one person was seriously hurt in the blast and four others were evaluated for minor injuries. The worker that was seriously injured is believed to be suffering from a concussion and chemical burns. However, given the state of the building after the blast, it’s a miracle that more people weren’t hurt in the accident. “It was significant structural damage. Three very large windows were blown out and thick, fortified doors were forced open by the blast,” Warren Mayor James Fouts told The Detroit News. “Our fire commissioner said the blast went straight up in the area where they test lithium batteries. The building was stuffed with personnel and equipment, but it was designed very well.” About 80 people work in the Tech Center. The battery explosion comes just months after the NHTSA opened an investigation into the Chevrolet Volt for battery fires. The NHTSA ultimately closed the case in January after discovering no safety flaws, but the Volt has struggled to shake its perceived image as a fire hazard. The Volt enjoyed a record month of sales in March, but it’s possible the latest explosion could rekindle those safety fears, even if the battery involved was unrelated to the Volt itself.