Santo Dominico, Dominican Republic — The deaths of eight American tourists in the Dominican Republic this year are not part of a mysterious wave of fatalities but a medically and statistically normal phenomenon that has been lumped together by the U.S. media, the island's tourism minister said Friday. Autopsies show the tourists died of natural causes, tourism minister Francisco Javier García told reporters.

With some 3.2 million U.S. tourists visiting the Dominican Republic last year, he said, it's not unusual for eight people to die while on vacation over any six month period. Dominican officials say they are confident the three deaths still under investigation were also from natural causes.

He said five of the autopsies are complete, and three are undergoing further toxicological analysis with the help from the FBI because of the circumstances of the deaths. A U.S. State Department official told CBS News that the FBI's assistance came at the request of Dominican authorities and that personnel arrived on June 20.

During a Friday press conference, García expressed his frustration at "having to give two press conferences in 15 days." He called for fair treatment and appeared defensive. "There are other countries with more [U.S.] victims but nobody names them," García said.

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García said the number of U.S. tourist deaths in the Dominican Republic dropped 56% from 2016 to 2018, although he did not provide further numbers or details. The U.S. State Department also discounted the idea of a surge of tourist deaths, saying the agency had not seen an uptick in the number of U.S. citizen who died there.

García showed reporters a summary of pathologists' findings in each death but declined to share the autopsy reports, saying they are not public records and that only the families could authorize their release.

The Dominican government has been criticized for not being more forthcoming about the details of the death investigations.

In response to public concerns, authorities are increasing internal security measures at hotels as well as increased control over food and beverages, but only as a preventive measure, García said.

"We're very sorry for the families' grief," he said. But "there is no wave of mysterious deaths."