Authorities in Fiji said Tuesday that a young Texas couple vacationing in the South Pacific country died from an unidentified illness. The couple arrived in Fiji on May 22 and were taken to a hospital after they became ill, according to Fiji's Ministry of Health and Medical Services.

The ministry said in a statement their conditions worsened despite medical care and they died within a few days of each other. According to the Fiji Broadcast Corporation, the two Americans died in the city of Nadi.

The ministry said it was working with police forensics, the World Health Organization and the U.S. Centers for Disease Control and Prevention to try to determine what caused the deaths. The ministry said it had put in place public health measures, although didn't immediately identify what those were.

David and Michelle Paul, from Fort Worth, Texas. Facebook

Texas television station WFAA identified the couple as David and Michelle Paul, from Fort Worth. The couple had a 2-year-old son and David Paul had a daughter from a previous relationship, according to the station.

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David Paul was an Air Force veteran and the couple was physically fit, relative Tracey Calanog told WFAA.

Calanog said the couple loved to travel and had been organizing the Fiji trip for some time: "They were planning an amazing vacation," she said. She said the couple's children were with relatives.

The U.S. Embassy in Fiji said in a statement it had been working closely with the Fiji government, police and health officials for more than a week to investigate the deaths. According to Fiji Broadcast Corporation, the embassy said it is not aware of any specific public-health threat to the community.

"We appreciate the efforts made thus far by the Fijian authorities and stand ready to provide further assistance, if requested," the embassy said.

Fiji is home to just over 900,000 people and is a popular tourist destination thanks to its warm climate, white sand beaches and coral reefs.