Dillons grocery store employees stand in the parking lot after a bomb threat in Hutchinson. An unknown telephone caller made the bomb threats to the store on Tuesday, demanding that customers and employees disrobe and that the store wire money to his bank account. No bomb was found, and the FBI thinks the threats are part of an extortion scam that has hit stores across the country.

Hutchinson ? Large grocery and discount stores across the country have been targeted by a caller who threatens to blow up shoppers and workers with a bomb if employees fail to wire money to an account overseas, authorities said.

On Tuesday, an unknown telephone caller making bomb threats to a Dillons grocery store kept more than 100 people hostage, demanding they disrobe and that the store wire money to his bank account.

Police safely led the 46 employees and 64 customers, some of whom had taken off their clothes, out of that store Tuesday after about 90 minutes. Threatening calls also were made to a second Dillons store that same day in Hutchinson, which was evacuated without incident.

On Wednesday, three similar calls came in to Dillons stores and one to a Wal-Mart, said Police Lt. Steven Nelson. Police still are unsure whether Wednesday’s incidents were linked or copycat crimes.

No one was injured and no money paid, police said.

In Newport, R.I., on Tuesday a bomb threat caused the evacuation of a Wal-Mart and led employees to wire $10,000 to the caller. FBI spokesman Rich Kolko said the incident appeared related to a plot in recent days targeting banks and stores near Phoenix, Detroit, Salt Lake City and Philadelphia.

Kolko said Wednesday that the bureau was looking into whether the calls were being placed from overseas and was compiling reports from local police departments to look for similarities between the cases. “At this point, there’s enough similarities that we think it’s potentially one person or one group,” he said.

The caller to the Hutchinson store where more than 100 people were held appeared to have visual access to the store. The caller demanded the female hostages take off their clothes and after 20 minutes made a similar demand of the males.

Jim Peterson, one of the hostages, said some complied out of fear.

The caller also demanded that one of Store manager Mike Piros’ fingers be cut off for every hour his demands were not met, and another employee got a butcher knife on his orders. Peterson told the Hutchinson News that people became distraught.

“People came undone and started saying, ‘No, no,”‘ he said.

Piros was not harmed. Police there initially said they were investigating whether the caller had hacked into the surveillance system, but later backed away from that possibility.

No bomb was found.

Dillons spokesman Sheila Lowrie said the company brought counselors to the scene.

“We’re sorry the employees and the customers had to go through this,” Lowrie said.

The first of the threats that federal investigators are aware of came last Thursday at a Safeway in Sandy, Ore. The caller initially said he had a gun and was watching the store, but after meeting resistance to his demands he claimed to have a bomb, Sandy police Chief Harold Skelton said.

In Buchanan, Mich., on Monday, the caller directed employees of a Harding’s market to lock the front doors, move to the front and told them not to call police, said Berrien County Sheriff Paul Bailey. The man claimed he could see some workers standing up, and ordered them to sit down.

“He’s just ad-libbing,” Bailey said. “He can’t see anything.”

Nonetheless, Bailey said, the employees were so afraid they wired the caller $3,000.

The caller has not gotten every store he’s called to give up money, but the FBI on Wednesday did not provide the total amount taken.