SAN MATEO COUNTY, Calif. (KRON) – Police in California have launched an investigation into the discovery of a car that was found buried in the yard of a Silicon Valley mansion.

Landscapers working on the property discovered the car Thursday morning, police said. Officials responded to the home, located in the town of Atherton, after receiving reports of the strange discovery shortly before around 9 a.m., the Atherton Police Department wrote in a Thursday press release.

Police also utilized cadaver dogs, who indicated a “slight” possibility of human remains in the vehicle, according to the release.

Investigators had found no human remains as of Thursday evening, but discovered “unused bags of concrete throughout the vehicle,” police said.

The car was believed to have been buried sometime in the 1990s, before the current homeowner took up residence in the house, police said. The homeowner is not under investigation, the Associated Press reported, citing Atherton Police Cmdr. Daniel Larsen.

Crime scene technicians were still working to get the vehicle out of the ground as of Thursday night.

A representative for the Atherton police was not immediately available to share any updates as of Friday morning.

Atherton is one of the wealthiest towns in the U.S., with about 7,000 residents within its nearly 5 square miles, the AP reported.

The Associated Press contributed to this report.