Employees at a Burger King in Coon Rapids, Minnesota, grabbed tire irons from their cars and smashed out 20 windows because a stranger on the phone told them to.

The caller claimed to be from the fire department and said the building would explode if they didn't act immediately.

Just before 9:30 p.m. on a Friday night, workers at the restaurant on Northdale Boulevard received a call from someone claiming to be with the fire department who told the manager they were detecting dangerous levels of gas.

Break the windows or the restaurant would explode, the caller warned.

The Hoax Had Convincing Details

The caller seemed to have knowledge of fire suppression systems and acted like he was monitoring the building remotely.

Employee Grewe later told reporters, "I guess I was a little scared. My other co-workers were doing it so I just followed along."

Police arrived after someone at a gasoline station next door called emergency services to report what appeared to be vandalism in progress.

Part of a Multi-State Pattern

A day before the Coon Rapids incident, a caller claiming to be from the fire department told workers at a Burger King in Shawnee, Oklahoma, that there were high levels of carbon monoxide in their building.

The pattern stretched back months. On January 31, 2016, the manager of a Morro Bay, California Burger King received a similar call.

When windows proved hard to break by hand, that manager drove his car through the plate glass window, causing $35,000 in damage.

Criminal Charges Possible

Police said whoever made the calls could be charged with felony terrorist threats and felony criminal damage to property.

One employee suffered a minor cut during the window-shattering in Minnesota, but no one else was hurt.

The gas-leak hoax had crisscrossed the country in recent months, hitting not just Burger Kings but also Jack in the Box and Wendy's locations in Arizona.

Christa Jones, whose son worked at the Coon Rapids Burger King but wasn't on duty that night, captured the human cost: "It's just a waste of time for everybody. They do this prank but it costs everybody money."