A phone call came in to the Kmart in Snellville on Thursday afternoon.

The caller said he wanted $8,000 loaded to disposable cash cards or he would blow up the store.

Similar calls were received last Thursday at 10 retail outlets in Savannah, law enforcement officials said Monday.

And at other retail outlets across the country in recent months, FBI spokesman Stephen Emmett said.

But all of the calls were bogus, authorities said. There were no bombs.

“It took us 40 minutes to sweep the building before we called off the search” for a bomb,” Snellville Police Lt. Ray Gunter told The Atlanta Journal-Constitution. “We also notified South Gwinnett High School across the street. You have to take (these calls) seriously, because you never know.”

FBI officials said the call to the Snellville store and the many others like it were part of an emerging and elaborate scam to get money through an untraceable source.

The way the scam went, an anonymous caller contacted a retail location that sells Green Dot MoneyPak cards, and threatened to use explosives, or harm employees or their families if the manager didn’t load multiple cash cards with a given amount of money.

Then the caller requested that the card numbers be read aloud over the phone.

“Green Dot MoneyPak cards are reloadable and available at most retail outlets throughout the country and, like money wire transfers, are just as untraceable,” Emmett said. “These cards are not associated with any bank, meaning that the money is in the card.”

None of the managers at any stores contacted with this scam gave in, however, authorities said.

Still, the incident in Snellville – a two-hour call with a sometimes angry man speaking in a foreign accent – was tense, Gunter said.

“We tried to keep this guy on the phone to see what we could get,” Gunter said, noting that local and federal cops had tapped into the call and were trying trace the source.

What they came back with was an internet phone number that originated overseas, authorities said.

“You could tell by the way he was talking, he had never been here,” Gunter said. “He didn’t know the names of streets or where things were.”

So police called his bluff.

“After this guy had been on the phone for a while, we could tell he was scamming them,” Gunter said.

Emmett said the Green Dot MoneyPak cards were the common denominator in all of the bomb hoaxes.

Authorities said these types of threats are common, although they don’t always involve bomb threats. At the end of the day, cash card users are reminded never to give out the information on the cards. They could give thieves and tricksters access to the money stored up on the card.

“This is the trend,” Emmett said. “These cards are vulnerable if the numbers are given out.”

Anyone with information regarding this scam or any of the threats is asked to file a complaint with the FBI at

www.IC3.gov.