No deaths were immediately reported.
Sun Prairie, a community of about 30,000, was shaken by a blast about 7:15 p.m. that sent a large plume of smoke and flames rising from the downtown area.
WE Energies spokeswoman Cathy Schulze said a contractor hit a gas main ahead of "a possible explosion." She said the utility's first responders were in the area working to shut off the flow of gas and make the area safe.
Dane County Sheriff's Office operations manager Paul Logan said some people were taken to hospitals, but that no deaths had been reported. Logan said the sheriff's office evacuated its communications center. He had no other details.
Firefighters from Sun Prairie and surrounding communities responded to the scene. Police blocked off downtown streets from traffic and onlookers. The area has several businesses including bars and restaurants.
Steve Owen, 60, who owns Sun City Cyclery and Skates in downtown Sun Prairie, said he saw firefighters and police officers on the street and then the explosion happened. He said the building across from his shop "literally lifted up."
He said the force of the blast knocked him back in his chair and that he ran outside and saw a ball of fire.
"People were scrambling," said Owen, who lives above his shop.
Jill Thompson, 56, who lives about two blocks from where the blast occurred, said, "It shook the whole building. I thought someone had hit the building with their vehicle. We seen the smoke immediately." The area is about half a block from City Hall.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)