Two visitors to an Oakland apartment complex found a decaying human head in the back yard and delivered it to a police station to be investigated, officers say. A headless corpse was recently found nearby.

When someone told Oakland, California, police on Friday they’d brought a severed human head to the downtown station, officers at first suspected a Halloween prank, KGO reported.

Then they took a closer look, the station reported.

“It was decomposed and had a little bit of flesh on it,” Sgt. Michael Cardoza told KGO. “I can say in my years of service I’ve never had a human skull delivered to the police station.”

Two visitors to an Oakland apartment complex had discovered the decaying head in the backyard earlier Friday morning, The San Francisco Chronicle reported. They decided to take it to police.

“They thought it was real enough that it had to be brought to our attention immediately,” Cardoza told KGO.

Investigators searched the apartment complex and interviewed residents, who said they had no idea how the head got there, KTVU reported.

“They come into my house while I’m eating dinner, they come in and tell me something about a head,” said tenant Manul Adrow, according to the station. “I don’t know nothing about no head.”

Others said they were stunned by the discovery, reported KNTV.

“My mother has been on the block for 47 years, my cousin lives right here, I can’t believe that,” said Oakland resident Lola Walker, according to the station. “I hope it’s not anybody I know.”

A badly decomposed body missing a head was discovered nearby in Oakland in September, and a headless body was found stuffed in a fish tank in San Francisco in August, reported The San Francisco Chronicle.

Cardoza said the Alameda County coroner’s office is working to identify the severed head and determine whether it’s linked to the headless bodies, the publication reported.

Police asked that anyone with information on the severed head call the Oakland Homicide Unit at 510-238-3821 or the tip line at 510-238-7950, reported The East Bay Times.