Update: 4:25 p.m.: APAC released the following statement regarding the incident on Prathersville Road on Monday:On the morning of June 13, 2011, at APAC-Missouri, Inc. TMs office and shop facility on 1591 East Prathersville Rd. in Columbia, Missouri, workers performing a cleanup operation discovered a magazine containing industrial explosives. APAC promptly reported the discovery to the Boone County Fire District, which together with Mid-Missouri bomb squad, has taken control of the area to assure safety, and will determine the disposition of the materials. APAC is fully cooperating with, and appreciates, the professional response of these officials. APAC was unaware of the presence of the magazine, does not utilize explosives at this facility, and understands that the explosive materials are possibly 25 to 30 years old, which is longer than APAC has owned the facility. APAC is investigating how the magazine came to be on its property, but to this point has reached no conclusions. Update: 3:45 p.m.: A construction company in Columbia was going through a scrap metal pile on their property on Monday when they found old explosives.Gale Blomenkamp, Battalion Chief of the Boone County Fire Protection District, said the dynamite was found on APAC's property on Prathersville Road.The business was looking through their scrap metal pile when they found a box that is used to store dynamite. The box was four feet tall and three feet around. Inside, they found seven sticks of three inch dynamite, blasting caps and detonation wires."This is the big stuff," Blomenkamp said. He noted it would have likely been used to blast rock or construction materials.Blomenkamp believes the items had been stored there for 25 to 30 years, before APAC had even purchased the property.After the explosives were discovered, Highway 63 was closed down to allow for a 1,000 yard diameter around the property. Officials removed the blasting caps and wires and then set the box on fire. There was no explosion in the incident."Old explosive gets very sensitive," Blomenkamp said. "It's better to burn it in place rather than to move it."Highway 63 reopened late Monday afternoon. Update 2:50 p.m Old explosives have been found in a constrution area near Highway 63 and Prathersville Road in Boone County, according to the Missouri State Highway Patrol.The highway is closed in the area as crews work to safely detonate the explosives.The Highway Patrol reports that the road could be closed for another hour. Orgininal Story, 2:35 p.m.: Highway 63 is closed in Boone County just north of Columbia near the Prathersville Road exit.Officials are not releasing deatails about the incident at this time.The Boone County Dispatch website is calling the closure an investigation. KRCG is on-scene and will have updates as they are available.