CNN
 — 

Authorities are investigating the unusual circumstances surrounding the discovery of a vehicle buried on a residential property about 30 miles south of San Francisco in Atherton, California.

The vehicle was discovered Thursday morning by landscapers working on a project for the current homeowner, according to a news release from Atherton Police Department.

“Due to the unknown nature of why the vehicle was buried, cadaver dogs were called to the scene,” the department said. “The cadaver dogs made a slight notification of possible human remains.”

San Mateo Crime Lab technicians are currently excavating the vehicle and no human remains have been found at this time, police said.

The vehicle was buried four to five feet underground with unused bags of concrete inside, according to Atherton police, who said they believe it was buried sometime in the 1990s, before the current homeowner occupied the home.

The motive and circumstances surrounding the burial of the car are being further investigated by authorities.