A Transportation Security Administration (TSA) agent's patch is seen as she helps travelers place their bags through the 3-D scanner at the Miami International Airport.

Three airport security screeners based at Mineta San Jose International Airport in California have tested positive for the new coronavirus, the first detected among Transportation Security Administration workers, the agency said Wednesday.

The three TSA agents are being treated for the illness and are quarantined at home, the agency said in a statement. Security checkpoints at the California airport are still open.

"The agency is working with the [Centers for Disease Control and Prevention], as well as the California Department of Public Health and the Santa Clara County Public Health Department to monitor the situation as well as the health and safety of our employees and the traveling public," it said.

U.S. airline executives this week reported a sharp drop in bookings, including for domestic travel, as more cases were detected in the United States, handing airlines the biggest crisis since the Sept. 11, 2001, terrorist attacks. They warned demand could get worse before it gets better.

The TSA recommended travelers put their personal items such as wallets, keys and phones in their carry-on bags instead of using a bin and to wash their hands before and after going through security.

"TSA will continue to follow guidance issued by the Centers for Disease Control and the Occupational Safety and Health Administration regarding workforce protection," the agency said.