At least two people were injured Tuesday in a chemical plant explosion in northwestern Wisconsin, authorities said.

The plant, owned by Cortec Corp., manufactures aerosols and paint solvents and has about eight employees.

"We had a small explosion unrelated to production," Cortec vice president Anna Vignetti said. "That's all we know right now."

The two injured workers suffered what were believed to be first- or second-degree burns, Vignetti said.

Vignetti said she did not yet know how much damage had been done to the plant. The facility, about 100 miles northeast of the Twin Cities, was shut down pending further investigation.

Two people were treated at the Spooner Health System emergency room and then transferred to other facilities, said the system's chief executive, Mike Schafer. The hospital had not received permission from the families to release the patients' conditions, he said.

Wisconsin Emergency Management spokeswoman Lori Getter said the plant was evacuated and emergency workers set up a two-block perimeter around it.

St. Paul, Minn.-based Cortec manufactures products for corrosion control.

Ruth Skeie, director of the Spooner Area Chamber of Commerce, said she could see smoke from the Cortec blast at her office a mile away.

Nearby schools were keeping children inside after the explosion, Getter said. Spooner has a population of about 2,700.