Investigators say it might take days to collect the remaining pieces of a human skeleton that turned up during routine construction at Wheeler Downtown Airport in Kansas City, Mo.

Police were called immediately Monday when workers unearthed the bones. The remains are believed to have been there "for quite some time," according to police, who began a "death investigation" after confirming the findings.

It's unclear whether the remains are those of a man or woman.

The airport has been operating since 1927. It is across the Missouri River from the historic River Market, an area reportedly known for organized crime activity in the early 20th century.

Service to the airport, which handles about 225 general aviation planes on a normal day, was not affected by the discovery. Planes continue to take off and land normally as the investigation continues.

(Image Credit: Kansas City Aviation Dept)