Another American tourist died this week at a resort in the Dominican Republic. Leyla Cox, 53, came to the island on June 5 to celebrate her birthday.

Her family said she was supposed to return home two days ago, but now, they're planning her funeral. Cox died on June 10, and according to her son, U.S. officials said she died of a heart attack.

At least six other Americans have died since January, some under questionable circumstances. Miranda Schaup-Werner and a couple from Maryland, Edward Holmes and Cynthia Day all died at Bahia Principe hotels.

Leyla Cox Facebook

Preliminary autopsies released by Dominican authorities said they all had fluid in their lungs and respiratory failure. The FBI is conducting toxicology reports on those three deaths.

The series of fatalities are causing concern among Americans thinking of coming to the island. According to the State Department, 13 Americans died there all of last year and three were considered homicides.

In a statement, the U.S. ambassador to the Dominican Republic said, "The safety and security of U.S. citizens that live in, work in, and visit the Dominican Republic remains our highest priority. These incidents are tragic and we offer our deepest condolences to those personally impacted."