Five other firefighters were injured as crews from across southern Wisconsin responded to the explosion.
A WE Energies spokeswoman says workers for a contractor apparently punctured a natural gas main, sending gas leaking into a building ahead of the explosion.
Fires are still burning after a massive gas line explosion in Sun Prairie, Wisconsin.
The first explosion happened around 7 p.m.at the Barr House building, shattering business windows along Main Street.
"Our hearts go out to the family of Cory Barr, captain of the volunteer fire department in Sun Prairie, who died in a gas explosion last night". Four other firefighters, a police officer and seven civilians were also hurt.
The official Facebook page of the City of Sun Prairie wrote: "All residents are advised to avoid downtown Sun Prairie".
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"We are hurt", Garrison said of his team's loss of one of its veterans, "but we will come back".
"They were not doing work on our behalf", Schulze said. Police said as of 11 a.m. Wednesday, no one had been reported missing. The Barr House and Glass Nickel Pizza exploded after the gas ignited, police said.
The Red Cross reported it was setting up a reception area for evacuees at Sun Prairie High School. He said the building across from his shop 'literally lifted up'.
"On behalf of the whole state, we say we love you", the governor said.
He said the force of the blast knocked him back in his chair and that he ran outside and saw a ball of fire.
The firefighter who was critically injured has been stabilized, Konopacki said.
"People were scrambling", said Owen, who lives above his shop. "I don't think his legacy is going to be forgotten, and I think the spirit that he embodies is essentially the spirit of Sun Prairie, and Sun Prairie's going to get through this as a community".