The fire that caused extensive damage to a business at 702 Princess Anne St. in downtown Fredericksburg early Thursday was ruled as accidental, fire officials said Friday.

“After a thorough investigation by the Fire Marshal’s Office, the point of origin was determined to be a room in the left rear of the structure. An electric space heater located in that room and placed too close to combustible material was the cause of the fire. The electric space heater was also plugged into an electrical extension cord,” according to a news release from Deputy Fire Chief Michael Jones.

It began shortly before 12:30 a.m. Thursday in a 21/2-story building at 702 Princess Anne St., which was occupied by The Old Blantons Store.

When city firefighters arrived, heavy fire was coming from the first and second floors of the building and soon spread to window frames and the interior of the building next door, at 700 Princess Anne St.

Firefighters had the fire under control in about 20 minutes, but were on the scene for six hours.

The two buildings were unoccupied at the time and no one was injured.

Jones said it’s not uncommon for a fire to be caused by a space heater. He said they are more common in residential homes than in commercial eatablishments. He emphasized making sure that when using a space heater that there is at least three feet of clearance around any space heaters and that they should be plugged directly into an outlet and not into an extension strip.

Here are some more tips:

• Keep at least three feet of clearance between your alternate heat source and anything combustible
• Do not keep or store combustible materials in closed areas or near a heat source
• Never leave a heater on when you are not in the room or when you go to sleep, and never leave children or pets unattended near a heating source
• If you use an electric heater, be careful not to overload the electrical circuit
• Avoid using electrical heaters in bathrooms as they may come in contact with water.
• Do not plug electrical space heaters into an extension cord.
• Only use heaters that have been tested to the latest safety standards and installed and used to the manufacturer’s recommendations.