Human remains dating back to the mid-1800s have been discovered near a historic building in San Francisco's Fort Mason area.
U.S. Park Service officials say the bones appear to be from several different people and were just a couple of feet underground. They were in a pile and not neatly arranged.
Crews removing soil contaminated with lead near the building site made the discovery Monday.
U.S. Park Service spokeswoman Alexandra Picavet says buttons and bottle pieces found along with the bones allowed officials to date them to somewhere between the 1850s and 1870s.
Researchers are now trying to determine why they were there and to whom they belong. An archaeologist monitoring the soil removal work is helping to catalog and document the discovery.