An explosion in a Milwaukee suburb demolished a church and damaged two homes Wednesday, injuring seven people, including three firefighters, authorities said. Road and sewer work was being conducted in downtown Oconomowoc before the explosion occurred around 1:30 p.m., said Bob Duffy, the city's economic development director. The blast and flying debris knocked over several workers, he said. WE Energies had received a call from a contractor about an hour earlier, saying workers smelled gas and may have hit a line, company spokesman Brian Manthey said. The company sent out a crew, and at least one of its workers was injured, he said. Another WE Energies spokesman, Rick James, said he did not yet know whether natural gas caused the explosion. But the company turned off natural gas service to about 150 customers in the area around First Baptist Church Oconomowoc, and emergency workers were evacuating nearby homes and businesses.