NORFOLK, Neb. — The largest steel manufacturer in North America and some of its plants in Nebraska are dealing with the fallout from a cybersecurity incident.

Nucor Corporation operates Nucor Steel Nebraska, Nucor Detailing Center and Vulcraft Nebraska in Norfolk. According to a filing with the Securities and Exchange Commission made on Tuesday, the company recently identified a cybersecurity incident involving unauthorized third-party access to certain information technology systems.

The filing said the company activated its incident response plan and took potentially affected systems offline, among other containment, remediation and recovery measures. 

“The Company is actively investigating the incident with the assistance of leading external cybersecurity experts and has notified federal law enforcement authorities,” the filing said.

Nucor temporarily halted certain production operations at various locations across the country. An official with Nucor in Norfolk confirmed the cybersecurity incident but couldn’t comment about how it was affecting operations. Trucks were still entering and exiting the facility on Wednesday morning.

NCN reached out to the Nucor corporate office for more details and did not immediately receive a response.

According to the filing, Nucor is in the process of restarting its affected operations.