The crew of a truck carrying a load of gold bars had just pulled off the interstate in North Carolina when, the two men told police, a seemingly ordinary episode of carsickness turned into a multimillion-dollar heist.

On Wednesday, authorities said they were suspicious that the roadside robbery might have been an inside job.

As soon as the guards stopped on the shoulder because one of them wasn't feeling well, three robbers drove up in a cargo van and confronted them at gunpoint, yelling "Policia!" and ordering the crew to lie on the ground. The robbers tied their hands behind their backs and marched them into nearby woods, authorities said.

The thieves then set out orange traffic cones while they gathered up 275 pounds of gold bars worth $4.8 million and fled, leaving the two guards stranded along Interstate 95 as drivers zoomed by.

Authorities released search warrants Wednesday in which detectives raised questions about the initial accounts of the heist.

"The fact that the truck was robbed immediately upon pulling over at an unannounced stop is suspicious in and of itself," the warrant stated, adding that the truck had no external markings indicating the cargo. The warrant said the suspects tried to steal the truck but could not get it started, indicating they did not know how to operate a commercial truck.

At a news conference, Wilson County Sheriff Calvin Woodard said the guards were still considered victims, not suspects, but that all possibilities were being investigated.

Asked to elaborate on the warrants that were filed the day after the heist, the sheriff said the documents were written in a hurry before the victims, who spoke little English, could be thoroughly interviewed in Spanish.

The strange scene unfolded around dusk Sunday in a rural area about 50 miles east of Raleigh.

Earlier in the day, the guards had stopped for gas in Dillon, South Carolina, near the North Carolina line. As they kept driving, one of them started to feel sick and said he smelled gas, Woodard said.

However, after deputies arrived, a mechanic found no problems with the truck, the sheriff said.

The guards got out of the tractor-trailer without their guns, according to the sheriff, who said it was a company security violation to leave the truck without their weapons.

Woodard said that the robbers cut a padlock, but there were no other security measures to stop them.

When the robbers were gone, the guards drew the attention of startled motorists, several of whom called 911 to report seeing uniformed men running into the highway with their hands bound, motioning for help.

"They've got their hands zip-tied behind their backs, and they're out in the road to try to flag people down to call the police," one caller said.

The caller described the scene to the dispatcher and waited in his car for at least 12 minutes for officers to arrive, according to recordings released by Wilson County authorities.

The man told the dispatcher he did not feel safe leaving his vehicle. One of the guards can be heard trying to relate details though his window.

The heist happened hours after the truck left Miami for a town south of Boston.

Neither guard was injured, according to their employer, Miami-based Transvalue Inc., which specializes in transporting cash, precious metals, gems and jewelry. A Transvalue spokeswoman declined to comment.

The company has offered a $50,000 reward for information leading to an arrest.

A woman who saw the guards walking into the road with their hands tied did not feel safe stopping.

"It's dark. It's raining, and they're walking in the middle of the road," she said. "I didn't know what to do."