PORTLAND Ore. (KPTV) – It seemed surreal to some residents of a southwest Portland apartment complex when they saw smoke billowing from the ground in front of one of their buildings on Wednesday night.

Shannon Campbell was in her apartment on Southwest Condor Avenue when her neighbor started screaming about the smoke billowing from the floor behind her apartment. Campbell ran to investigate and saw something odd.

“There was a round circle in the sawdust,” Campbell said. “It was smoke and it was black. It has a very strong smell of smoke.

Campbell said she tried pouring water on it, but that didn’t do much to stop the smoke.

“The top was cool but when I dug in it got hotter and hotter as I came down,” Campbell said.

Portland Fire and Rescue arrived and they quickly put more water on the smoke and dug up what was burning. Firefighters on the scene told Campbell the smoke likely came from sawdust in the mulch, which was mixed with the dirt, which spontaneously burned at high temperatures.

“They said at this time of year it happens quite often if you put some kind of chemical sitting on it for a while,” Campbell said. “The sawdust is combustible, I suppose.”

Campbell believes cleaning chemicals that leaked from awnings at his resort helped fuel the smoke. Regardless, the National Fire Association says spontaneous combustion fires are very common. More than 14,000 occur each year in the United States. Oil-soaked rags, cleaning chemicals and sawdust are blamed for starting most of these fires.

Although firefighters were able to keep the ground from smoking, Campbell said she will now keep an eye on the mulch outside her apartment. She also suggests that other people should also be careful, especially with the warm temperatures expected this week.

“When you have hot spells and dry wood and sawdust you have to be careful what you put in it and be careful to make sure that if it’s really dry you don’t put cigarettes in it. “Campbell said. “If you see smoke, it’s something you’ll probably want to dig out so it doesn’t smoke out the bottom.”

FOX 12 has contacted Portland Fire and Rescue for comment on the incident, but we have not heard back. They said people should store flammable chemicals in appropriate containers and cabinets that can regulate temperature. FOX 12 has also contacted Campbell’s apartment complex, but we have not heard back.