Roofers using an open-flame torch caused a fire Tuesday that destroyed a vacant house on Athens Street, fire officials said. No one was hurt.

The fire was at the corner of Martin Luther King Jr. Boulevard and Athens Street and blocked traffic on a portion of Athens Street that runs behind the Burger King restaurant in southeast Gainesville.

The 2,500-square-foot two-story brick house caught fire shortly before 3 p.m. Workers accidentally started the fire by using an open-flame torch to apply a tar-based roofing material, Gainesville Fire Chief Jon Canada said. The estimated value of damage to the house, which was a total loss, was $150,000, Canada said.

Firefighters at first made an interior attack on the fire, but had to retreat into defensive mode because of the heat generated by the fire on the second floor, he said. The roof collapsed and the second floor was gutted. The first floor had extensive smoke and water damage.

About 20 city firefighters and six Hall County firefighters battled the blaze. A ladder truck was used to put water on the second story.

The fire was finally knocked down at about 5:30 p.m.