Pilots and flight attendants are demanding airlines stop flights to China as health officials declare a global emergency over the rapidly spreading coronavirus, with American Airlines’ pilots filing a lawsuit seeking an immediate halt.

China has reported nearly 10,000 cases and 213 deaths, but the virus has spread to 18 countries, mostly, presumably, by airline passengers.

The United States has advised its citizens not to travel to China, raising its warning to the same level as those for Iraq and Afghanistan.

U.S. airlines, which have been reducing flights to China this week, were reassessing flying plans as a result, according to people familiar with the matter.

It is possible the White House could opt to take further action to bar flights to China in coming days, but officials stressed that no decision has been made.

The Allied Pilots Association (APA), which represents American Airlines pilots, cited “serious, and in many ways still unknown, health threats posed by the coronavirus” in a lawsuit filed in Texas, where the airline is based.

American said it was taking precautions against the virus but had no immediate comment on the lawsuit. On Wednesday, it announced flight cancellations from Los Angeles to Beijing and Shanghai, but is continuing flights from Dallas.