The San Francisco Police Department discovered chemicals to make explosives near an RV park Friday night.
"The resident of an RV was detained and nearby residents were evacuated," they added.
In Google Maps, the address provided by the police is listed as being on the same block as Candlestick RV Park.
"The SFFD and our EOD Unit responded to the scene," police said. "This appears to be an isolated incident and the investigation has been turned over to the department. Residents that were evacuated are receiving necessary assistance with temporary shelter."
They said the investigation is ongoing and is in its early stages. No more information is currently available.
The RV park did not answer the phone when ABC News reached out for comment.