Some U.S. and Canadian diplomats suffered injuries as serious as mild traumatic brain injury and likely damage to the central nervous system while stationed in Havana, CBS News reports.

WASHINGTON — CBS News is reporting that some U.S. and Canadian diplomats working in Cuba suffered injuries as serious as mild traumatic brain injury and likely damage to the central nervous system, according to medical records.

The diplomats were examined by a U.S. doctor after they complained about hearing loss, nausea, headaches and balance issues. They were subjected to other types of harassment while stationed in Havana including vandalism to vehicles, surveillance and home break-ins, CBS News reports.

The Associated Press has reported that in the fall of 2016, a series of U.S. diplomats began suffering unexplained losses of hearing, according to officials with knowledge of the case. Some of the diplomats’ symptoms were so severe that they were forced to cancel their tours early and return to the United States, the officials said.

The officials told The Associated Press that the hearing loss appeared to have been caused by the deliberate use of some sort of sonic device operating outside the range of audible sound.

Former diplomats who previously served in the communist nation reported similar attacks dating back to the 1980s including pets who were poisoned and rodents nailed to doors.

Read the full CBS report and see video here.