FORT WORTH, Texas (AP) — Health officials in Fiji said they don’t yet have an answer on why a Texas couple died while vacationing on the island but that influenza has been ruled out as a potential cause.

Fiji’s Ministry of Health and Medical Services said in a statement Wednesday that the investigation is ongoing into the deaths of 38-year-old David Paul and 35-year-old Michelle Paul, but that officials don’t believe the public is at risk. The couple died within two days of each other after falling ill from an unknown ailment.

Michelle Paul’s father, Marc Calanog, told the Fort Worth Star-Telegram this week that the couple met five years ago in Hawaii and that both loved beaches and snorkeling. He said the couple had planned to visit Fiji from May 19 to May 27, settling on that time because family members could watch their two young children.

Calanog said he got a text message from Michelle on May 24 that said: “We are both going to doctor now. We have been throwing up for eight hours. David also has diarrhea. My hands are numb.”

He said he got a call on May 25 that Michelle was dead, and that David Paul was dead two days later.

“I did not think it was so serious,” Calanog told the newspaper. “I was stunned. I almost cried, but I didn’t cry because I was holding onto my emotions. … I would say I was emotionally shocked.”

David Paul, an Air Force veteran, worked as an engineer at Lockheed Martin in Fort Worth, a company spokesman said. Michelle Paul worked for Marriott International, according to the company.

The ministry in Fiji said staff and health workers who were in contact with the couple are being monitored as a precaution, but that all are currently well. The ministry said it’s also working with local police, the World Health Organization and the U.S. Centers for Disease Control and Prevention to determine the cause of death.

“It would be premature to speculate further on the cause of death until the investigation is complete,” the statement said.

The CDC said Wednesday that they’re working with the government in Fiji to investigate, which will include testing specimens in CDC laboratories.