San Francisco police confirmed Tuesday evening that bones were found at a home in the city's Haight-Ashbury neighborhood during a search in connection with the 1984 disappearance of 10-year-old Kevin Collins.

Representatives from the FBI, San Francisco police and the Alameda County Sheriff's Office served the warrant early Tuesday morning at a home near Masonic Avenue and Page Street and remained at the scene into the evening, police spokesman Officer Albie Esparza said.

The SFPD's mobile command center arrived at the scene at around 6 a.m., according to neighbors.

In a press release issued regarding Tuesday's investigation, police said cadaver dogs indicated the presence of possible remains under the concrete floor of the garage.

According to police, the concrete was removed and several bones were located. The San Francisco Medical Examiner's Office responded to the scene and assumed custody of the bones.

Police said preliminary assessment of the bones indicated that they are from an animal and not human in origin, but that further analysis of the bones was necessary.

Investigators with San Francisco's cold case unit were seen walking out of the home at around 4:30 p.m, but they refused to comment on the search.

Earlier Tuesday, KTVU spoke with Kevin's mother, Ann Collins, who said she received a call from the San Francisco Police Department warning her that something was going on. She said police confirmed that the search had found something that is being sent to the state crime lab for analysis.

Ann Collins said that the discovery felt like it came from out of the blue, especially occuring only days after what would have been Kevin's 39th birthday.

The search for Collins that came after his original disappearance was one of the first missing child stories to gain national attention and laid the blueprint for many subsequent missing children cases. The searches for Polly Klaas, Amber Swartz, Ilene Misheloff, and Michaela Garecht would all follow a similar pattern.

Posters with Kevin's picture sprung up on telephone poles, billboards, milk cartons and even national magazine covers as people in the Bay Area -- and later, the entire country -- searched, hoping and praying along with his family for the boy's safe return.

Police said that the investigation is ongoing and the search warrant would remain under seal.  As of about 7 p.m., most of Masonic Street remained blocked off as police continued their investigation at the home.