A Goodwill in Round Lake Beach, Illinois, was evacuated after workers found a training grenade inside a donation box.

According to a police press release, loss prevention officers at a Goodwill Store and Donation Center called 9-1-1 after they discovered the grenade among the hundreds of other items donated to the store.

Round Lake Beach police evacuated the store upon arrival before determining that the grenade was inactive.

Police said officers observed a small plug in the “hollowed-out section of the grenade” and were uncertain, so they called in a bomb squad just in case.

The Waukegan Bomb Squad also responded to the scene and used an X-ray machine to examine the grenade. Investigators determined the grenade was inactive and nobody was in danger.

Police say practice or training grenades are hollowed-out grenades often sold on the internet.

Round Lake Beach Police Chief Wayne Wilde warned the public to avoid donating weapons to Goodwill stores or similar places.

“While it’s great to donate unused items you may not need to places like Goodwill and the Salvation Army, people should never donate firearms or diffused explosive devices to these places,” Chief Wilde said. “People who find or wish to discard these items should contact their local police instead, and the police department will assist in the safe removal of these devices, if needed.”

Police are investigating as to how the grenade ended up in the store’s donation pile.

Round Lake Beach is located about 50 miles northwest of Chicago.