ROCKY MOUNT,Va. -

The Rocky Mount Fire Department is working to figure out what caused a fire at the Ply Gem manufacturing plant.

The fire department got the call around 10 o'clock Sunday night. When they arrived they found heavy smoke coming from the office portion of the building. With the help of the sprinkler system, crews were able to extinguish the fire quickly.

A fire official says there was extensive damage to that part of the building, but it did not affect production.