Charles and Joan Bachman had heard the rumors. When the couple considered buying an empty field in the hamlet of Schuylkill Haven, Pennsylvania, nearly 20 years ago, some townspeople told them that the plot might have had a former life as a cemetery. The Bachmans purchased the meadow anyway. Almost two decades later, they now know the rumors were true.

Last Thursday a contractor for the Pennsylvania Department of Transportation working on the widening of Route 61 through the small village 90 miles northwest of Philadelphia made a disturbing discovery on the edge of the Bachmans’ property. A heavy rain that had drenched Schuylkill Haven the night before had also washed away the soil on a sheared highway embankment. The erosion revealed human bones embedded in the ground in what looked to be a mass grave, and construction was halted as soon as the worker spotted them.

“One looked like a tibia, which is the long bone of the lower leg, definitely a partial mandible, which is the jaw bone, and we identified that because of the anatomic location of the tooth socket. Then there were fragments of the skull plate,” Schuylkill County Coroner Dr. David J. Moylan III, whose office was called in to investigate, told the Pottsville Republican Herald.

According to Reuters, research by Pennsylvania Department of Transportation archaeologist Kevin Mock found a connection between the Bachmans’ meadow and its earlier use as an unmarked burial ground during the deadly 1918 Spanish flu pandemic, which claimed an estimated 50 million lives—3 percent of the world’s population. In the dying days of World War I, the dying came to eastern Pennsylvania as the flu swept through in October 1918 and caused schools, shops and even hospitals to close. According to the Pottsville Republican-Herald, approximately 17,000 residents in the region around Schuylkill Haven fell ill. Close to 1,500 of them died, leaving as many as 3,000 children orphaned.

Death was so prevalent that casket makers could not keep up with demand. Many victims were buried without coffins, particularly the impoverished whose bodies were thrown into unmarked burial grounds such as the one unearthed in Schuylkill Haven. “They could not make caskets fast enough, and they used to bring bodies in here, dig holes, lay the bodies in and put lime down,” Schuylkill County Deputy Coroner Joseph Pothering told local television station WFMZ.

The day after the discovery, cadaver dogs arrived at the scene to sniff for human scents while forensic archaeologists from Mercyhurst University in Erie, Pennsylvania, excavated the embankment and screened the soil for bone fragments. Authorities said the exposure of the mass grave is no threat to local residents as the lime buried with the bodies made it unlikely that active flu pathogens could exist nearly a century later.

The excavated remains were taken to Mercyhurst University for medical examination and possible DNA extraction. It could take several weeks for the results of forensic tests to come back. Once that work is complete, there are plans to give the victims a proper burial in a county cemetery. “They are going to take the bones, do some DNA work and give these proper burials and hopefully we get some information from them, who, when and why and notify families,” Pothering told WFMZ.

Although hundreds of flu victims could be buried beneath the field, the county coroner’s office decided it would be best to remove only the remains in the exposed area near Route 61 and leave the remainder of the bodies undisturbed. The landowners agree. “What is there, I think they should leave there, not to go back any farther. They have been there for 100 years,” Joan Bachman told WFMZ.