A band of men pulled off a jewelry heist worth at least $500,000 on a southern Minnesota interstate just after midnight, and the robbers are still at large.

A victim told authorities that he and six employees had been traveling back from a jewelry and diamond trade show in Chicago when they pulled over at a rest stop on I-90 between Highway 52 and the town of Eyota, said Capt. Scott Berhns of the Olmsted County Sheriff's Office.

After five of them went inside to use the bathroom – the other two stayed back – a van that had been following them hundreds of miles pulled up and four men in black jumped out, smashed the windows and took several suitcases loaded with jewels, according to Berhns.

Acknowledging that 350 miles was a long distance to follow someone, Berhns said, "If your uncle called you in Chicago and said, 'I'm going to give you $500,000 before I die,' would you drive down there? I would. So we have to remember it's a lot of money. That would certainly be enough incentive for criminals to do that."

Police found the suspects' abandoned van a mile away in a ditch off the interstate, but failed to locate the robbers, Behrns said.

The sheriff's office is not yet releasing the names of the victims or where they are from to protect their safety.