The History Center of Freeborn County got a potentially explosive surprise Wednesday when staff found not one, but three live grenades among its collection dating back to the 1960s.

Executive Director Stephanie Kimble said a curator was cataloging a box from the Albert Lea-based center's collection that morning when she came across a grenade.

Staff didn't know whether the grenade was live so they called city police, Kimble said. In turn, officers contacted the St. Paul police bomb squad members, who traveled to Albert Lea that afternoon to remove the grenade.

Meanwhile, staff checked their archives and found two other live grenades — all donated sometime during the 1960s.

While officers stood by, staff closed the History Center and moved to other parts of the building.

"It was a little exciting," Kimble said, chuckling.

Finding grenades or other live munitions among museum collections is not rare: Last week, the Connecticut State Library was evacuated after archivists discovered two live World War I-era grenades. And a museum in Covington, Ky., briefly shut down this year when staff found an inactive Japanese grenade from World War II.

In Freeborn County a few years ago, History Center staff even found a case of kerosene among its collection.

Back then, Kimble said, historical societies and local museums didn't have the same standards in accepting donations compared with today.

"Most of them were run by volunteers, so there really wasn't that best practice in place," she said. "As those things change, quite often items that have already been collected sometimes get forgotten."

The History Center of Freeborn County embarked on a massive audit of its collection starting in 2019 as staff looked to change some of the museum's exhibits, including one that had been in place for about 40 years.

It's a drawn-out process, however. The center has cataloged about 30,000 items thus far, and Kimble estimates another 30,000 to 40,000 items still need rechecking.

The project has been worthwhile as staff find new ways to put together exhibits that can be switched out every year or two, though they've discovered a new rule to follow.

"Now we're going to be looking for anything that might explode, apparently," Kimble said. "Just make sure you deactivate your grenades before you bring them to the museum."