TULALIP — The new Tulalip Resort Casino officially opened its doors Aug. 15.

At about 3:43 a.m. Aug. 17, Marysville Fire District crews responded to what they said was a small fire on the 10th floor of the still sparkling new hotel.

After using a stairway to reach the 10th floor, firefighters discovered the fire already was extinguished, according to fire district Public Information Officer Stephanie Price.

Price said the hotel sprinkler system had activated and apparently put out the fire, which officials believe possibly was ignited by discarded smoking materials left in a planter box near the hotel elevators.

The incident was under investigation by the Snohomish County Fire Marshal’s Office as of the deadline for the this issue. A damage estimate was not available.

Due to the fire, Price said hotel staff temporarily evacuated the 9th, 10th and 11th floors of the resort.