• A spate of retailers have been hit by bomb threats in recent months, The Wall Street Journal reported.
• The threats are being made by people demanding ransoms in the form of money, bitcoin or gift cards.
• Retailers affected included Walmart, Kroger, and Whole Foods, the Journal reported.

Some of America's biggest retailers have been hit by a string of bomb threats in recent months, The Wall Street Journal reported.

Stores, airports, political organizations, and schools receiving threats are not unheard of, but the bomb threat calls to retailers have come with a new twist: demands for money, bitcoin, or gift cards, according to the report.

Walmart, Kroger, and Whole Foods stores across the country are among those targeted with threats and ransom demands this year.

A Whole Foods outlet just outside of Chicago received a call demanding $5,000 in bitcoin, and threatening to set off a pipe bomb in the store, the Journal reported.

A Kroger-owned store in New Mexico was also evacuated after an employee took a call demanding money be wired, and threatening that a bomb would be detonated if she called the police, per the newspaper.

"We can confirm suspicious activity at several Kroger locations," a Kroger spokesperson told Insider. "The safety and well-being of our associates and customers are our top priority. We are working closely with local law enforcement and the FBI to investigate similar threats that have taken place around the country at many retail stores."

A Walmart spokesperson declined to comment, and referred Insider to its comments to the Journal, which said the company cooperates with local, state, and federal investigators in the incidents.

On the same day in May, two Meijer locations in Wisconsin reportedly received similar threats, hours apart. The second threat, made to a location in Grafton, Wisconsin, also demanded $5,000 of Apple gift cards, per the report.

In all these incidents, no suspicious packages or explosive devices were found.

A public information officer in the Grafton police department told the Journal that attempts to obtain money or gift cards over the phone were usually scams – but nevertheless could not be ignored. 

Whole Foods recently told managers to go over bomb threat protocols with employees, according to a memo seen by  the newspaper.

Other threats have also been made to retailers in recent months. A group of Target stores across several states were evacuated earlier this month after bomb threats were sent to local news outlets.

The threatening messages were tied to Target's handling of the backlash to its Pride Month collection of products and clothing.

Rodney McMullen, the CEO of Kroger, told the outlet it took threats seriously and was working with police and the FBI, and Whole Foods said it was guided by law enforcement officials. 

Whole Foods and Meijer did not immediately respond to requests for comment from Insider, made outside normal working hours.

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