Two miners are unaccounted for after a roof collapsed at the Cargill salt mine in Avery Island, LA on Monday morning, local news organizations reported.

“We have two employees who remain unaccounted for at this time and we are working with local first responders and the Mine Safety and Health Administration who are onsite to respond to this emergency,” Cargill said in a statement to local CBS News affiliate KFLY .

16 other workers who were present at the time of the collapse evacuated the site without injury, the company said. Cargill has halted operations at the salt mine as an investigation into the incident is carried out.

A report by The Acadiana Advocate noted that Cargill’s salt mine has been issued over 50 safety citations by Mine Safety and Health Administration inspectors in 2020.

The Avery Island mine is one of three salt mines operated by Cargill in the United States, according to information on the firm’s website. Its other mines are located in Lansing, NY and Cleveland, OH.