A southern Minnesota history center avoided an explosive exhibit on Thursday when authorities helped remove three live World War I-era incendiary devices that had sat undiscovered in the collection for more than half a century.

The museum closed to the public, and they called volunteers and asked them not to come in until the issue was resolved.

A recent incident at the History Center of Freeborn County in Albert Lea, Minnesota, involved the discovery of live grenades, sparking concerns about legal consequences and the safe handling of such items.

The History Center of Freeborn County got a potentially explosive surprise Wednesday when staff discovered not one, but three live grenades among its collection dating back to the 1960s. Executive Director Stephanie Kimble said a curator was cataloguing a box from the Albert Lea-based center’s collection when she came across a grenade Wednesday morning.