A married couple from Tennessee who owned a travel agency were among the three Americans found dead at a resort in the Bahamas.
Royal Travel was owned by Michael andRobbiePhillips. The Sand Lady, as she was called, specialized in arranging trips to Sandals resorts. She posted photos of the beach on her Facebook page, saying she was there with her husband.
The third victim was a resident of Florida. Donnis was in a hospital in Florida and remained in serious condition.
The visitors' samples have been sent to a lab in the U.S. to help authorities understand what happened.
The police commissioner of the Bahamas, Paul Rolle, said that officials collected samples from the rooms where tourists were staying and the surrounding property to determine if there were any problems.
He said that they really want to know what happened.
The couples had been staying in two separate villas at the Sandals Emerald Bay.
Rolle said the results of the toxicology study would be expected in about a week. The Department of Environmental Health and police officers are still at the resort.
Rolle said he was not going to speculate on what might have caused the tourists deaths.
Four tourists went to a doctor the night before their bodies were discovered and they had complained of feeling unwell. He said they had different things to eat.
The original statement from Sandals Resorts stated that it is supporting the investigation and the families of those affected.
The company said that they can't give further information at this time out of respect for the privacy of their guests.
In Washington, State Department spokesman Ned Price said that three American citizens had died and offered his sympathies to the families.
We stand ready to provide all appropriate consular assistance, and we are closely monitoring the investigations into the cause of death.
Seven years ago a Delaware family became seriously ill at a resort in the U.S. Virgin Islands. The resort used a banned pesticide called methyl bromide several times and was blamed by the U.S. authorities.
Michael Catalini is a reporter for the Associated Press.