Thirteen people were taken to a hospital for treatment after being sickened at a West Michigan medical supply manufacturing business, officials said.
The cause of the illnesses Tuesday night wasn't immediately known.
Crews responded about 9:45 p.m. following reports of employees having trouble breathing at Aspen Surgical in the Caledonia area, about 15 miles southeast of Grand Rapids. They evaluated or treated 63 people at the scene and 13 were taken to a hospital.
Caledonia Township Fire Chief Brian Bennett told reporters it wasn't known what caused the health problems. Bennett said people reported respiratory problems, headaches and other conditions, and those hospitalized had improved.
A message seeking updated information from Bennett was sent Wednesday morning by The Associated Press.
A hazardous materials team that responded didn't find hazardous chemicals in the air, but the facility was ventilated. Fire crews cleared the scene early Wednesday, and turned the response over to Aspen Surgical. A message was left Wednesday morning at the business.
According to its website, Aspen Surgical manufactures and sells needles, instruments and other medical supplies.