Arson units are trying to figure out what caused a fire at a house in northeast Houston.

The fire started around 10:30 p.m. Wednesday at a home on Firnat and Bertwood.

When firefighters arrived, the flames was already shooting out of a window and parts of the attic.

Firefighters made a fast attack and were able to put out the fire quickly.

The house was vacant, so no one was injured.

Firefighters believe the fire was deliberately set.