Washington Sen. Maria Cantwell's office said Wednesday a D.C.-based staffer has tested positive for COVID-19. It's the first known case on Capitol Hill.

"The individual has been in isolation since starting to have symptoms," according to a release from Cantwell's office. "On the advice of the Attending Physician, the senator has closed her Washington, D.C. office this week for deep cleaning and staff will be teleworking."

The Washington Democrat's office said Wednesday night the staffer who tested positive has "no known contact with the senator or other members of Congress."

Cantwell has requested that other staffers who may have been in contact with the infected employee also be tested.

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