I did nearly 30 years ago. The little box stove was very hot. Then
I started hearing the airflow. It got loud and I cut the air intake
totally although I wasn't totally sure that I was having a chimney fire.
After a few minutes it stopped. I didn't call the Fire Dept but
probably should have. [Neighbors told me flames were shooting up 30
feet and airplanes were avoiding the area. :-)]

Charles Schuler wrote:
Creosote is flammable.

As anyone who has ever had a chimney fire will attest to ;)