On Christmas Eve, few years ago, we woke up to very loud sirens and fire alarms. Our next door neighbor's tree went up in flames at 3 am. They had left the lights on all night. The tree was at the bottom of their stairs. So they could not get down to the first floor and they had to jump out of the 2nd story with their grandkids. But they had a detached garage and were able to jump onto the roof. [ they threw pillows down first then jumped onto them][grandpa had broken ankle, thats it]
I could not believe how fast the 2nd story went up in flames. The trucks were there last but it was a very hot fire. I don't even like to turn on the tree lights anymore.
also, lesson learned from that. DO NOT put a tree alongside the bottom of a stairwell. Firemen said it was like a perfect fire storm for the smoke and heat to go up the tunnel created by the stairwell.