A southern Utah wildfire that burned down an outbuilding and threatened five homes began Tuesday when chemicals from a person's shed overheated in the 100-degree weather and burst into flames.

The fire began Tuesday afternoon near La Verkin, where a person was cleaning out a shed, Utah fire officials said.

The person “disposed of chemicals that became inadvertently mixed and assisted by the 100-degree temperature caused spontaneous combustion to occur,” fire officials wrote in a news statement.

With high temperatures and almost no humidity — 6%— the fire spread rapidly to 19 acres.

Crews fought the fire from the ground and with aircraft. As of late Tuesday, it was about 80% contained, fire officials said.

“With the continued hot, dry weather, fires can be easily ignited,” fire officials wrote.

No one was injured in the fire, and residents were not forced to evacuate.