DULUTH — A St. Louis County public works crew doing exploratory archaeological digging in Duluth has unearthed several wooden coffins, but authorities said they contain no remains.

The excavation work was done to check for human remains in advance of a road project next to a cemetery that served as a burial site for about 5,000 people who died at the former St. Louis County Poor Farm between 1891 and 1947.

One bone was found outside of the coffins. Authorities suspect it’s from a grave relocation project in the 1960s.

A team of archaeologists in the next couple of weeks will determine if there are any other bones in the area. The Minnesota Indian Affairs Council and the state archaeologist office will coordinate and pay for the additional study.