A Pennsylvania construction worker recently stumbled on a mass grave, believed to contain the remains of people killed in the 1918 flu pandemic. 

Jenna Lee and Eric Shawn discussed the fascinating find with Tom Drogalis, executive director of the Schuylkill County Historical Society. 

Drogalis said the remains are a reminder of a "dire" time in the county, when 1,600 people died of Spanish influenza in a month in that area. 

For example, he said there were a shortage of caskets, so people would have to chain them to keep them from being stolen right off their property. 

Drogalis said that the small towns were overwhelmed, with many doctors and nurses serving in World War I. He said areas were quarantined, while schools and churches were shut down as authorities struggled to contain the outbreak. 

Drogalis called it a "sterling example" of how quickly an airborne virus can spread, expressing concern that the country remains ill-prepared for another outbreak.

Years later, scientists confirmed that an H1N1 flu virus was responsible for the historic pandemic, which claimed 50 million lives around the world.

Mercyhurst University sent a team of forensic archeologists to the site to investigate and gather bones for DNA testing.

Watch the "Happening Now" segment above.