(NEXSTAR) – Authorities have identified the three U.S. tourists who died at a Sandals Resort in the Bahamas after falling mysteriously ill. Samples taken from all three tourists have been sent to a U.S. lab to help determine what happened.

Officers were called to the Sandals Resort on the island of Exuma Friday morning after one of the tourists, a man, was found unresponsive in a villa, the Royal Bahamas Police Force said in a statement.

On their way to the resort, officers were told two more unresponsive tourists, a woman and a second man, had been found in a separate villa. All three were pronounced dead at the resort, with the woman and second man both showing “signs of convulsion,” local officials said.

A fourth tourist, a woman, was flown to a hospital.

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The three victims have been identified as Michael and Robbie Phillips of Tennessee and Vincent Paul Chiarella of Florida. Chiarella’s wife, Donnis, was the woman flown to a hospital. She has been airlifted to Florida but remains in serious condition.

The Tennessee couple is from Maryville, where they ran a travel agency that worked with Sandals, Nexstar’s WATE has learned. The agency has been recognized with multiple awards and accreditations from the Sandals Travel Agency Recognition Awards.

A Facebook post from Thursday, purportedly posted by Robbie Phillips, even shared admiration for the views in the Bahamas.

Samples were taken from the tourists, their rooms, and the nearby property to help identify whether any contaminants were present.

Health Minister Michael Darville said Saturday that some hotel guests went to a clinic Thursday with nausea and vomiting, were treated, and left. He said initial investigations indicate it was an isolated incident.

Chiarella’s son, Austin, spoke with ABC News last week and said his parents had been staying at the resort for their anniversary. Donnis told her son she fell ill Thursday but felt “she was alright” after leaving the clinic, ABC News reports.

Acting Prime Minister Chester Cooper issued a statement Friday saying that police are investigating and foul play “is not suspected.”

Minister of Health and Wellness Dr. Michael Darville told Eyewitness News Bahamas the team investigating these deaths “have a theory” regarding what happened but are still working to determine the exact cause. Authorities continue to believe these are isolated cases.

The U.S. State Department is monitoring the investigation and is “ready to provide all appropriate consular assistance,” a spokesperson told The Hill.

In a statement to Eyewitness News Bahamas, a representative for Sandals said, “Nothing is more important to Sandals Resorts than the safety of our guests. It is with deep sadness that we confirm the passing of three of our guests at Emerald Bay Resort on May 6, 2022. A health emergency was initially reported and following the protocols, we immediately alerted emergency medical professionals and relevant local authorities to provide support and investigate the situation.”

The company said it is cooperating with the investigation.

The Associated Press contributed to this report.