WARREN, Mich. (AP) -- Two employees were injured Wednesday in a lithium battery explosion that forced the evacuation of about 80 others at a General Motors Co. facility north of Detroit, authorities said.
The explosion at the Alternative Energy Center laboratory at the GM Tech Center in Warren also caused a small fire that was quickly extinguished.
The Tech Center, a sprawling 1950s-era campus, is home to the battery laboratory for the Chevrolet Volt electric car, but GM said in a statement that the explosion was "unrelated to the Chevrolet Volt or any other production vehicle."
"The incident was related to extreme testing on a prototype battery," the automaker said. Authorities are investigating.
Dispatchers received calls about the explosion at 8:46 a.m. and firefighters arrived five minutes later, Warren Fire Chief Dave Frederick said.
"They reported light smoke ... and some small amount of fire," Frederick said. "It was confined to the room of the explosion."
One worker was taken to an area hospital, while the second was treated at the scene. The extent of their injuries was not immediately known. Five employees also were being evaluated by medical personnel at the scene, GM said.
A hazardous materials team was called in to monitor the air quality at the facility, Frederick added.