— The FBI and Wilson County authorities are investigating the theft of an estimated $4 million worth of gold reportedly stolen during an armed robbery along Interstate 95 near Wilson Sunday evening, the sheriff's office says.

Two armed security guards told authorities that they were traveling from Miami to Massachusetts with a shipment of silver and gold when they pulled over at mile marker 114 after mechanical problems with their truck.

The sheriff's office says the guards reported that three armed men in a white van approached them, ordered them to the ground, tied their hands behind their backs and forced them to walk into some nearby woods.

Investigators, who responded to the scene shortly before 7 p.m., said the men then reportedly took three barrels of gold and left while the guards were in the woods.

It was unclear what form the gold was in, and the sheriff's office declined a request for an interview Monday morning.

But at gold's current value of about $40,000 per 1-kilogram bar, that could mean as many as 100 bars, or about 220 pounds.

A spokeswoman for the FBI said agents are looking to figure out if a federal crime occurred.

The guards are employed by TransValue Inc., which according to its website, is a Miami-based company that transports valuables between financial institutions.

Owner Jesus Rodriguez said he was unable to comment about the matter but confirmed the guards were driving a tractor-trailer. Neither was injured, he said.

The company is cooperating with authorities and is offering a $50,000 reward for any information that leads to an arrest.

Investigators ask that anyone with information to call the Wilson County Sheriff’s Office at 252-237-2118.