A person was found dead after a vehicle plowed into a health club in downtown Portland, Oregon, early Saturday morning, police said. Investigators later found explosives inside the car.

Portland police and the Portland fire and rescue department responded to the Multnomah Athletic Club shortly before 3am after the vehicle crashed through the front entrance and caught fire. Once the blaze was brought under control, a person was found dead inside the vehicle, police said in a statement.

An explosive disposal unit was called in after evidence of an explosive device was discovered, police said.

Sources said the driver of the vehicle was a former employee of the club, the Oregonian newspaper reported. According to investigators, one of the sources said, the former employee – allegedly disgruntled and with mental health issues – rented a car on Friday, which he used to drive into the building and around the first floor of the facility before setting off the explosive devices, believed to be a mix of propane tanks and pipe bombs, the Oregonian reported.

The club’s first floor housed a casual restaurant, formal event spaces, a members’ lounge overlooking Providence Park, a retail store and the front desk. Other amenities included workout rooms, pools, a rock-climbing wall, an indoor track, various sport courts and three other restaurants.

A club spokesperson, Adam Linnman, said in a statement that the crash occurred when the club was closed and that no club members or staff were injured. He said club officials deferred to local and federal authorities for additional details.

A note on the club’s website said the facility “will remain closed until further notice” and asked members and neighbors to avoid the area until the investigation was complete. “Our team is cooperating fully with the Portland Police Bureau and Portland Fire & Rescue, who are leading the investigation. Out of respect for that process, we will defer to them for additional details,” the statement said.

Special agents from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives also were responding, that agency said.

The Multnomah Athletic Club bills itself as the largest private athletic and social club in the US, founded in 1891 and boasting more than 21,000 members.