State Fire Marshall Sterling Lewis identified the victim as the store manager. All that remained of the business was a pile of splintered debris.
The explosion occurred as emergency workers were investigating a report of a propane leak. Authorities believe the gas fumes drifted into the store, where they somehow ignited, Lewis said.
Bystanders said there was an odor of gas before the explosion, reports CBS News affiliate WVNS.
Ghent Elementary, which is about a mile away from the school, suffered minor damage in the explosion, adds WVNS.
Tuesday's blast also killed a volunteer firefighter, a building inspector and two other people in this rural community.
Four other people were hospitalized with burns and other injuries. The victims included a building inspector and a volunteer firefighter.
State Fire Marshal Sterling Lewis said an aboveground tank of propane was being worked on at the time of the blast. The gas apparently drifted into the business and exploded. Cold temperatures would have kept the gas close to the ground.
"It is our initial thought that the fumes entered into the building and had to have an ignition point," Lewis said.
The propane tank and the store's underground gasoline tanks did not explode.
The U.S. Chemical Safety Board was sending a team to assess the site. The board makes safety recommendations to industry, labor groups and regulatory agencies.
The store's parent company, Little General Inc., would not comment.