The Detroit News reported a GM spokesman said one person was injured, but Warren Fire Chief Dave Fredericks said two were injured.
The Detroit Free Press said a woman working in the lab was taken to St. John Hospital and Medical Center in Detroit. A man working farther away from the explosion was being treated locally. The Free Press said smoke forced the evacuation of about 80 workers.
Fredericks said crews were searching for other fires caused by the explosion, and a HAZMAT team was at the scene.
"We received a call at about 9 a.m. that a battery had exploded at the tech center," Fredericks told the News. "We responded and found two victims and a small fire. At this point, I don't know the extent of the injuries, but the more serious of the two was taken to St. John Hospital on Moross Road."
The explosion took place in a battery research lab.
"We're aware of an incident this morning at one of our labs at the GM Tech Center that required a fire and emergency response," GM spokesman Greg Martin said. "All employees are accounted for, and we're trying to learn more details and we'll share them when we can."
Fredericks said it was the first time his department has been called to the tech center for an exploding battery. The tech center tests battery technologies.
The risk of battery fires in post-crash Chevrolet Volts was recently investigated by the National Highway Traffic Safety Administration. GM said it is replacing the 120-volt charging cords in most of the Volts it has sold since late 2010 to offer more consistency in charging.