(CNN)Three Americans found dead at a Sandals resort on the Bahamas' Great Exuma island on May 6 died due to carbon monoxide poisoning, local authorities said Tuesday.
"At this juncture of the investigation, we can officially confirm that all three of the victims died as a result of asphyxiation due to carbon monoxide poisoning," the Royal Bahamas Police Force announced in a news release. "This matter remains under active investigation."
No signs of trauma were found on the bodies, police previously told CNN, and Bahamian acting Prime Minister Chester Cooper had said foul play was not suspected. Police would not comment beyond the cause of death for all three US citizens in the latest news release.
The Americans -- Michael Phillips, 68, and his wife, Robbie Phillips, 65, from Tennessee, and Vincent Paul Chiarella, 64, from Florida -- died over the course of one evening. Chiarella's wife, Donnis, 65, was airlifted to the nation's capital of Nassau for further treatment before being transferred to Florida.
The two couples had reported feeling ill the night prior and were seen by medical staff, Bahamas Police Commissioner Paul Rolle said in May, and had eaten at different locations.
Staff discovered the couples in separate villas the following morning and alerted police.
In a statement on Wednesday, Sandals Resorts spokesperson Stacy Royal said, "Ensuring the safety and wellbeing of our guests and team members is and will always be paramount.
"We have taken additional measures such as engaging environmental safety experts for a comprehensive review of all systems across the resort. In addition, CO detectors have been placed in all guest rooms at Sandals Emerald Bay and detectors will be installed in all guest rooms throughout the portfolio."