The Maine Center for Disease Control offices at 286 Water Street in Augusta on Sept. 10. Credit: Natalie Williams / BDN

A dozen inmates at the state prison in Windham have tested positive for COVID-19.

The 12 inmates, who tested positive with the rapid antigen test and are awaiting confirmation from a second test, are being housed in a quarantine unit, Maine Department of Corrections officials said in a statement on Thursday.

The Maine Center for Disease Control and Prevention began an outbreak investigation at the prison on Tuesday. Staff have begun universal rapid testing for all staff and inmates at Windham, officials said.

The prison has suspended outside visits and cancelled transfers from other jails or prisons in response to the latest tests, officials said.