Authorities in the Bahamas have revealed what caused the deaths of three Americans at a resort in May.

The Associated Press reported that carbon monoxide poisoning killed a Tennessee couple and a man from Florida.

Royal Bahamas Police Force Commissioner Paul Rolle identified the victims as 68-year-old Michael Phillips, his wife 65-year-old Robbie Phillips and 64-year-old Vincent Chiarella.

According to the AP, Chiarella's wife, Donnis, was airlifted to a hospital in Nassau before being transported to a hospital in Miami.

The news outlet reported that they were staying next to each other in separate villas in the same building at the Sandals Emerald Bay resort on Great Exuma Island.

It's unknown if there were carbon monoxide detectors in the villas, and if they were working or not, according to the AP.

The news outlet reported that the night before their bodies were discovered, police said all four went to a doctor and complained of feeling ill.