A crisis over a mysterious ailment sickening US diplomats and their families – which began in Cuba and recently appeared in China – has widened as the State Department evacuated at least two more Americans from China, Independent reported.

The Americans who were evacuated worked at the US Consulate in the southern city of Guangzhou, and their colleagues and family members are being tested by a State Department medical team, officials said. It is unclear how many of them are exhibiting symptoms, but a State Department spokeswoman said on Wednesday evening that “a number of individuals” had been sent to the United States for further testing.

For months, US 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.