PORTLAND, Ore. (AP) — One person is dead following a fiery crash at a health club early Saturday in Portland, Oregon, according to authorities who also said explosive devices — some of which had detonated — were found.

Portland Police Bureau Chief Bob Day told reporters this appeared to be an isolated event. It occurred shortly before 3 a.m. at the Multnomah Athletic Club. The facility bills itself as the largest private athletic and social club in the U.S., founded in 1891 and boasting more than 21,000 members.

Police said the person who died was found inside the vehicle after the fire was contained. But details shared by local and federal law enforcement during a Saturday afternoon news conference were sparse.

Jim DeFrain, a police officer and supervisor of the Metro Explosive Disposal Unit, said propane tanks were among the items found. He said investigators believe the explosive materials were brought in by the vehicle.

A club spokesperson, Adam Linnman, in a statement, said the crash occurred when the club was closed and that no club members or staff were injured.