Ted Wachholz couldn't believe his eyes: He opened Facebook on Saturday morning and saw film footage of the SS Eastland disaster, which claimed 844 lives on the Chicago River in 1915, the Chicago Tribune reports.

"I'm reasonably confident that this is the first opportunity that the public has had" to see footage of the disaster, says Wachholz, who heads the Eastland Disaster Historical Society.

One clip (here, starting at the 1:10 minute mark) shows firefighters, volunteers, and police officers walking on the capsized ship, which was about to go to Indiana for a Western Electric employee picnic when it tipped over while tied to a dock, CBS Chicago reports.

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"It was a free-for-all early on," says Wachholz. "Anyone who was able to help out and contribute was jumping to the scene." A second clip (here, starting at 9:10) shows the righted ship a week later.

Wachholz figures the footage was taken by a professional (considering how expensive cameras were back then) from a small boat or raft floating nearby. What's more mysterious is how the footage cropped up: A US doctoral candidate found the footage, which is housed at a Netherlands film institute, while doing online research for his dissertation on Chicago during the First World War.

The clips were spliced between footage of marching soldiers and ceremonies, and it's not clear how it got there. "That's part of the intrigue, part of the mystery behind even having this footage available," says Wachholz.

The student then posted his find on the historical society's Facebook page. The footage itself gives him "chills" and "goose bumps," Wachholz tells MyFox Chicago.

"I don't think I've ever had an experience quite like that before." (Secrets of a 1629 mutiny and massacre were recently unearthed.)

This article originally appeared on Newser: Mystery Footage Found of 1915 Eastland Disaster

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