The United States is evacuating several Americans from China amid concerns that they are suffering from a mysterious illness due to strange noises. In May, the United States had urged its citizens in China to remain alert after an American citizen working at its consulate in the city of Guangzhou suffered a mild brain injury after months of experiencing abnormal sensations of sound and pressure.

The State Department had deployed a medical team to screen other employees and family members at the US consulate in Guangzhou following this incident. “As a result of the screening process so far, the department has sent a number of individuals for further evaluation and a comprehensive assessment of their symptoms and findings in the United States,” State Department spokesperson Heather Nauert was quoted as saying by Reuters.

“Medical professionals will continue to conduct full evaluations to determine the cause of the reported symptoms and whether the findings are consistent with those noted in previously affected government personnel or possibly completely unrelated,” she added.

Secretary of State Mike Pompeo said on Tuesday that the department has established a task force “to direct a multi-agency response to the unexplained health incidents”. He added: “The precise nature of the injuries suffered by the affected personnel, and whether a common cause exists for all cases, has not yet been established.” The United States has also not yet revealed how many people are being evacuated.

The medical indications were “very similar” and “entirely consistent” with those experienced by American diplomats posted in the Cuban capital of Havana, Pompeo had said last month.

In September, the US had ordered more than half of its diplomats to leave Cuba, a year after they began to describe unexplained health problems. At least 21 of them and their families reported traumatic brain injuries and permanent hearing loss.

The symptoms of illness have varied from person to person. In addition to hearing loss and concussions, some experienced nausea, headaches and ear-ringing, and some now suffer from problems with concentration and word recall. Cuba denied being behind the unexplained attacks.