The authorities said that a car containing at least one explosive device crashed into an athletic club in Portland, Ore., early on Saturday morning, killing the driver.

The cause of the crash and the driver’s motive were not immediately known. The police did not identify the driver.

Portland Fire and Rescue responded to a report that a car had crashed through the front entrance of the Multnomah Athletic Club and caught fire around 3 a.m., according to Terry Foster, a spokesman for the department.

After the fire was under control, emergency responders found one person dead in the car, the Portland Police Bureau said in a news release.

The authorities then found “evidence of an explosive device” in the car. The police bureau’s explosives disposal team was called to assess the scene.

The police advised the public to avoid the area near the club, which overlooks Providence Park in Portland’s Goose Hollow neighborhood.

A spokeswoman for the Portland Police Bureau declined to provide additional information.

The Multnomah Athletic Club said on social media that it expected a prolonged closure after a “serious incident.” The club added that it did not have a timeline for reopening, but said that it was cooperating with the authorities.

It was not immediately clear whether any employees or members of the club were injured. The club did not immediately respond to a request for comment on Saturday afternoon.

The facility is among the largest athletic and social clubs in the United States, according to its website. The 600,000-square-foot, eight-floor facility has multiple restaurants, swimming pools, athletic courts and banquet facilities.