Investigators focused on an area behind the building and examined photos that witnesses took before fire crews arrived, Fire Marshal John Jennings said.

Fire crews were called about 5:55 p.m. Saturday to a back porch fire at the Jefferson Business Center on U.S. 221 in Forest, and when they arrived seven minutes later the attic was engulfed in flames, Forest Fire Department Chief Todd Styles said. Only the building's brick walls were left standing.

No one was injured, and firefighters from Bedford and Campbell counties as well as Lynchburg had the blaze under control by about 8 p.m., Styles said. They closed U.S. 221 between Graves Mill and Cottontown roads until about 10:45 p.m. to make room for fire equipment and water lines.

The building housed five businesses including Virginia Farm Bureau, Scene 3 Boardshop and Blackwater Bike Shop, according to the Carrington Properties Web site. The suites were each between 1,050 and 2,120 square feet.

Jeff Gray, the owner of Scene 3, said he had recently cancelled the skate shop's insurance because he was planning to move to a new location on Kemper and 14th streets in downtown Lynchburg. The 36-year-old has a wife and two young children, he said, and his future livelihood is unclear.

Jennings did not release a cause of the fire. He said he expected the investigation to conclude early this week.

-- Jorge Valencia