As of Monday afternoon, 120 inmates and 21 staff at Snake River Correctional Institution near Ontario, Ore., have tested positive for COVID-19, according to the Oregon Department of Corrections online tracking tool.

That's a massive increase from about a week ago on July 4, when just seven staffers and two inmates had tested positive, according to figures reported by Oregon Public Broadcasting. It appears to make the prison the third-largest workplace outbreak in Oregon, behind the Oregon State Penitentiary in Salem—another prison—and Pacific Seafood in Newport.

Thousands of inmates have been quarantined at Snake River since the outbreak began. Right now, 2,768 are under quarantine and 242 have been tested for the virus, meaning nearly half of all test results have come back positive.

Department spokeswoman Jennifer Black said the spike in cases occurred over the weekend. Black says she does not yet know if any inmates at Snake River have been hospitalized for the virus.