The GlaxoSmithKline Consumer Healthcare Manufacturing plant in Aiken shut down operations this morning, and there is no indication when they will resume.

The decision to shut down plant operations was made after a presence of "elevated methane levels" was detected in the sewer system at the site on Windham Road, according to Teresa Caro, a spokeswoman for GSK. Employees in the plant were evacuated immediately, and other areas of the site have been cleared for safety and security purposes, Caro said in a statement. No safety risk was posed to the surrounding community.

"We have communicated to employees that they are not expected to return to work until we have fully addressed this issue," Caro said. "Managers have been in contact with their teams and all employees and are encouraged to check in with the site before leaving for work."

Authorities and a small maintenance crew, led by the Center Fire Department, remained at the site investigating the issue this afternoon.

The site employs about 200 people and manufactures about a dozen pharmaceutical products.