The first coronavirus case in the U.S. Capitol has been diagnosed. A staff member for Washington Senator Maria Cantwell has tested positive for the disease, her office said in a statement.

Cantwell's office said that the individual has been in isolation since symptoms appeared. The Capitol's attending physician advised Cantwell to close her office for the rest of the week and have the office deep-cleaned, which the Washington Democrat is doing.

The individual has not had known contact with the senator or any other members of Congress. Cantwell is requesting testing for anyone who had contact with the individual and has symptoms of coronavirus infection.

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Cantwell's home state has by far the largest number of coronavirus cases in the U.S. There are at least 281 cases and more than 25 people have died of the disease in Washington state.

Congressional leaders are considering temporarily halting tours of the U.S. Capitol as a result of rising concerns over the spread of coronavirus.

Arden Farhi and Nancy Cordes contributed to this report.