Three American tourists died from a mysterious respiratory illness in a Dominican Republic hotel, according to several reports.

Maryland tourists Edward Nathaniel Holmes, 63, and Cynthia Ann Day, 49, both died Thursday inside a hotel room after they collapsed and experienced respiratory failure, ABC News reported.

WBAL reported that both tourists were scheduled to leave on Thursday.

Within five days, Miranda Schaup-Werner, 41, of Allentown, died of the same respiratory illness at the same hotel after she had a drink at the Bahía Príncipe’s minibar, the New York Post reported.

“It was, at first, a little confusing that there was such a strong parallel … it immediately caused serious concern for us,” said Jay McDonald, a spokesperson for Schaup-Werner’s grieving husband, Daniel Werner.

“They died five days after, and the cause was determined to be the same, this just puts this whole thing through the stratosphere — something is going on, and we want to know what it is,” McDonald added.

American and Dominican authorities are actively investigating the tourists’ deaths.

“The U.S. Embassy is actively monitoring the investigations by Dominican authorities into these tragic deaths,” officials said.“We stand ready to provide assistance as requested.”

The Dominican Republic National Police confirmed that Schaup-Werner died from respiratory failure and pulmonary edema, and an autopsy from medical examiners revealed that the couple died from the same causes.