Armed robbers stole $4 million worth of gold off a Massachusetts-bound truck traveling on Interstate 95, North Carolina authorities say.

The Wilson County Sheriff’s Office said Monday two security guards working for Miami’s Transvalue Inc. reported three gunmen descended upon their truck while it was parked on the side of I-95 Sunday evening. The security guards said they had pulled the vehicle over after experiencing maintenance problems.

The gunmen were reportedly driving a white van.

After ordering the guards to the ground, the robbers proceeded to tie their hands behind their backs and march them into some nearby woods.

With the guards out of the way, the three male suspects carried out the daring heist, unloading multiple barrels filled with gold before fleeing the scene.

The Federal Bureau of Investigations has joined forces in the investigation.