A fire in downtown Ortonville, Minn., destroyed two businesses and damaged a third in the heart of the city's historic district.

Fire officials said a telemarketing company, DCC Solutions, and the Once and Again Thrift store were gutted by the early morning blaze Wednesday, which also damaged a Radio Shack store.

All three buildings were part of a historical district that had received a state historical grant to pay for renovations.

The telemarketing firm, which employed about 50 people, was located in what used to be the city's only large department store.

Fire Chief Randy McClain said firefighters from several communities did their best to keep the fire from spreading from DCC Solutions to the thrift store but couldn't.

McClain said an explosion, probably not caused by a natural gas leak, accompanied the fire and blew out windows across the street from the burning buildings.

No one was injured in the fire, he said.

The state Fire Marshal's Office is expected to send an investigator to the scene Thursday. McClain said determining a cause won't be easy because of the extensive damage.

By early Wednesday afternoon, construction crews had knocked down most of the ruined businesses.

Ortonville, located on the Minnesota-South Dakota border, has about 1,800 residents.

The Associated Press contributed to this report. Bob von Sternberg • 612-673-7184.