Major civic construction projects often turn up bones but they usually turn out to be either fossilized remains of ancient creatures or sometimes remains of natives. However the SAPD had no choice but to start a homicide investigation after contractors working on the OC Streetcar project found what have been deemed to be human remains at a former recycling yard located at 2008 West 5th Street, which is in the Artesia Pilar Neighborhood, according to the SAPD’s Twitter account.

An anthropologist assigned to the project said the bones appeared to be human and they appeared to have been buried six feet in the ground, according to CBS.

Investigators used a drone to survey and take photos over the site of the discovery before attempting to retrieve the human remains Wednesday afternoon. What appeared to be a rib cage as well as arm and leg bones had been partially unearthed as of 4 p.m., according to the O.C. Register.

There are probably more bones at the site, which was a residential area before it became a recycling yard.