A man may have set fire to an apartment accidentally while trying to burn a huge spider, reports the American press.
The fire occurred on Sunday in an apartment block in the city of Redding, in northern California.
A witness who lived on the floor where the fire occurred told a local newspaper that the burning spider could have spread the fire around the apartment.
It is not clear if the spider survived the fire. No injuries were reported but the block was evacuated.
The head of the local fire department, Gerry Gray, confirmed to the BBC that there had been a fire in an apartment block, but that the cause of the fire was not yet "determined".
"Information about the spider was presented by civilian witnesses, at the scene of the fire, and it's certainly part of our investigation," Gray said.
The spider was a "huge wolf spider," according to a witness cited by the local newspaper Redding Record Searchlight that lives in the department where the fire occurred.
The fire department told the newspaper that the fire seemed to have started with a blowtorch.
Redding, where the incident occurred, is 162 miles (261km) north of the state capital, Sacramento.
Witnesses say that the spider spread the fire when it scurried on a nearby mattress.
The fire in the mattress was extinguished by the residents, but had already spread t or other parts of the floor.
Officials said the fire caused damage for about $ 11,000 (£ 8,000) and that some apartments in the building were "uninhabitable."