KNOXVILLE, Tenn. (WATE) – Multiple outlets reported Wednesday the three American tourists who were found dead in the Bahamas in May, including a couple from East Tennessee, died from carbon monoxide poisoning.

Robbie Phillips, 65, and her husband Michael Phillips, 68, of Maryville, Tenn., and Vincent Paul Chiarella, 64, of Florida were found unresponsive at the Sandals Emerald Bay resort on Exuma on Friday, May 6. The Royal Bahamas Police Force said in a statement released Tuesday that they died from asphyxiation due to carbon monoxide poisoning.

Chiarella’s wife, Donnis, survived and was airlifted to a hospital in Florida in serious condition.

The couples were staying in separate villas next to each other in the same building at the Sandals Emerald Bay resort on the island of Exuma. It was not clear if the villas had carbon monoxide detectors and if they did, whether they were working, according to the Associated Press.

In response to the deaths, the resort has placed CO detectors in all guest rooms at Sandals Emerald Bay and plan to place detectors in all guest rooms throughout the region. The resort also partnered with “environmental safety experts for a comprehensive review of all systems across the resort.”

Bahamas Minister of Health & Wellness Dr. Michael Darville told ABC News that some hotel guests went to a clinic on Thursday, May 5 with nausea and vomiting, were treated and left.

Investigators said no foul play was suspected. Royal Bahamas Police Force officials did not provide additional details Wednesday and said the deaths remain under investigation.