Smoking was believed to be the cause of a northwest Houston apartment fire.

Flames broke out in an apartment at the Coppertree complex on West Gulf Bank at Veterans Memorial shortly before midnight Thursday.

The fire gutted one of the units.

Houston firefighters said the couple inside the burned unit was smoking and suspect a cigarette sparked the flames.

"The fire appears to have started from smoking in bed," said Kevin Carley with the Houston Fire Department. "We arrived on scene and had fire coming from a downstairs unit. The fire was contained to just that one unit."

The couple got out of their apartment safely.

No injuries were reported.

The apartment was destroyed.