Arson investigators are trying to figure out what caused a hotel fire in southwest Houston.

The fire broke out around 2:30 a.m. Monday in a third floor unit at the In Town Suites on Branch Forest and Highway 6.

A maintenance worker was inside at the time, but was able to make it out safely.

He had bystanders call 911.

When firefighters arrived, they didn't have to connect their hoses because the sprinkler system in the room was able to put the fire out.

The room suffered minor smoke and fire damage, according to fire officials.

No word yet on what caused the fire to start.