A crisis over a mysterious ailment sickening American diplomats and their families — which began in Cuba and recently appeared in China — widened on Wednesday. The State Department evacuated at least two more Americans who fell ill in China after hearing strange noises, officials said.

Many other employees at the American Consulate in the southern Chinese city of Guangzhou and their family members are also being tested by a State Department medical team that has been flown in, officials said. It is unclear how many of them are exhibiting symptoms, but officials expect more American personnel to be evacuated.

For months, American officials have been worried that their diplomats have been subjected to targeted attacks involving odd sounds, leading to symptoms similar to those “following concussion or minor traumatic brain injury,” the State Department says.