SAN JUAN, Puerto Rico (WKRN/AP) — A couple from Maryville, Tennessee are among the three American tourists who died at a resort in the Bahamas under mysterious circumstances.

Samples extracted from three have been sent to a lab in the United States to expedite results and help authorities understand what happened, officials said Monday.

The police commissioner of the Bahamas, Paul Rolle, said officials also collected samples from the rooms where the tourists were staying and the surrounding property to determine whether any contaminants were present.

“We really want to know what caused this,” he said.

He identified the victims as Michael Phillips, 68, and wife Robbie Phillips, 65, of Tennessee, and Vincent Paul Chiarella, 64, of Florida.

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

Their bodies were found Friday morning at the Sandals Emerald Bay resort in Exuma, where the couples had been staying in two separate villas.

The samples were sent to a lab in Philadelphia, with results of the toxicology study expected in about a week, Rolle said. He noted that the Bahamas’ Department of Environmental Health and police officers are still at the resort.