VAIL, Colo. -- Vail police said a mysterious black box attached to the underside of an SUV turned out to be a tracking device planted by a private investigator in a divorce case.

Authorities said a witness reported seeing a man crawl under an SUV in front the Vail Gymnastics Center at about 5:30 p.m. Thursday, crawl back out and then drive away.

Officers found a black box under the vehicle and summoned the Jefferson County bomb squad from Golden, Colo.

They ordered the evacuation of a nearby gymnastics center, where a dance recital was under way, and an elementary school where some children were having a sleepover. Part of the north frontage road of Interstate 70 was closed as a precaution.

A license plate number led police to Dave Alan Stark, 52, of Silt, Colo. Police said he acknowledged planting the tracking device, and agreed to remove it. He was arrested when he arrived, and was booked for investigation of criminal tampering.

The bomb squad was turned around shortly before it arrived in Vail.

Sark is the owner of Aspen Country Process Services in Glenwood Springs, Colo.