Delta Air Lines Inc. and American Airlines Group Inc. are halting service to China due to health concerns from the coronavirus outbreak, as a flight suspension spreads to the U.S.

Flights to Beijing and Shanghai will cease today and resume March 27, American said in an email Friday, a day after the U.S. government warned people not to travel to China. Delta said it would would halt service starting Feb. 6 to give customers looking to leave China a way to do so. Delta will restart flights April 30.

The shutdown of air links between the U.S. and China is deepening the disruption from the coronavirus, which has been declared a global health emergency by the World Health Organization. The halt of flights to Beijing and Shanghai underscores the rising concern, since both cities are hundreds of miles from the focus of the outbreak around Wuhan in China’s central Hubei province.

Before the U.S. government issued its warning, United Airlines Holdings Inc. announced plans to pare service to China but hadn’t halted all flights. European carriers including British Airways, Air France and Deutsche Lufthansa AG had already announced plans to stop flying to China.

American, which will continue flying to Hong Kong, said it would work to reaccommodate passengers after the immediate halt to service to Beijing and Shanghai. The company’s pilots union sued the airline Thursday in an effort to stop China flights and called on members to refuse to fly there.

Delta currently operates 42 weekly flights between the U.S. and China, including daily service connecting Beijing and Detroit and Seattle, and Shanghai and Atlanta, Detroit, Los Angeles and Seattle. The carrier had already announced plans to cut service in half.