The plant, located off US Highway 60, confirmed on Twitter it is “experiencing an operational emergency”.
Emergency services in Armstrong County, Carson County, as well as the Amarillo/Potter/Randall Office of Emergency Management, and the Texas Department of Public Safety, have all been notified and are responding.
Officers from the Carson County Sherrif’s Office are closing roads in the surrounding area.
No injuries have been reported, while Pantex Plant said residents off-site have been unaffected.
The on-site response effort is being conducted by the Emergency Response Organisation, a trained group of employees at the plant with detailed knowledge of its operations and emergency response procedures.
These staff represent functions at the plant including security, logistics, safety, medical response, radiological assessment and firefighting.
The Pantex Plant, which employs more than 3,300 full-time employees, is the main nuclear weapons assembly and disassembly facility in the US.
It aims to maintain the safety, security and reliability of the nation’s nuclear weapons stockpile.
The 2,000-acre facility, built in 1942, is located on an 18,000-acre site, 17 miles northeast of Amarillo, in Carson County, Texas.
It is managed and operated for the US Department of energy by Consolidated Nuclear Security and Sandia National Laboratories.
In January 2010, Pantex Plant was put on lockdown when a lab worker reported seeing two men wearing camouflage and carrying rifles exit a vehicle a “couple of miles” away.
The men were found to be employees on their day off, goose hunting on private property.
This is a breaking story. More to follow.