St. Louis — About 1,000 people were evacuated from Harrah’s St. Louis Casino and Hotel this morning after a fire started inside an exterior wall.

Pattonville Fire Department Battalion Chief Robert Murray said that the casino called around 9 a.m. saying smoke was filling a stairwell. The fire broke through the building’s outer wall and was quickly extinguished by a crew waiting outside, Murray said.

Hotel senior vice president and general manager Michael St. Pierre said he didn’t yet have an estimate of damage and no one was injured.

Firefighters believe the source of the fire was a cigarette thrown into mulch.