A Centers for Disease Control and Prevention technician may have been exposed to live Ebola virus after a laboratory error discovered on Tuesday.

The CDC will also check whether other employees were exposed to the virus and will monitor the exposed technician for 21 days, the length of the disease’s incubation period. The exposed technician was reportedly wearing a smock and gloves, but no facial mask.

A CDC lab that handles live Ebola in Atlanta, Georgia, sent samples of the disease to a different CDC lab on Monday. Those samples were supposed to contain “inactivated” Ebola, according to The New York Times.

But the samples may have contained live Ebola, something the second lab is not equipped to handle.

Thomas Frieden, director at the CDC, said last summer that the agency had used unsafe practices while handling samples of flu and anthrax. Members of the House of Representatives’ Energy and Commerce subcommittee questioned Frieden about the agency’s safety procedures on Capitol Hill. He admitted the mistakes were more than isolated incidents, and pledged to resolve the greater problem.

The CDC has blamed the anthrax incident on poor management oversight. The head of the lab responsible for the mistake has since resigned.

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