(CNN) At least 10 American citizens have died after an apparent sudden health issue in the Dominican Republic since June 2018, according to the US State Department, victims' relatives and the resorts involved.

Officials in the Dominican Republican or the US have not said the deaths are connected. Here's everything we know about the 10 people who have died -- and what the hotels and their relatives have said.

Vittorio Caruso, 56

Where he's from:

Long Island, New York

When and where he died:

It's unclear where Caruso died, but his sister-in-law Lisa Maria Caruso told CNN affiliate News 12 Long Island that he died on June 17.

The circumstances:

A US State Department official confirmed to CNN that a man died in the Dominican Republic in June, but did not provide details regarding his identity or the cause of death. Lisa Maria Caruso told News 12 Long Island that the family had received a phone call saying Vittorio was sick. Minutes later, she said, they received a second phone call telling them that he had died. She said Caruso was enjoying part of his retirement in the Dominican Republic after selling a pizza shop in Glen Cove that he had owned with his brother for 12 years.

Joseph Allen, 55

Where he's from:

New Jersey

When and where he died:

He died June 13 at the Terra Linda resort in Sosua, Dominican Republic, his sister Jaimie Reed told CNN.

The circumstances:

His sister said he was not feeling well when he was at the hotel pool with his friends. The friends told his sister he showered and went out that night, despite the fact that he still wasn't feeling well. The next morning, he failed to meet up with friends. When hotel staff checked his room, they found him dead. His son arrived in the Dominican Republic hours after his body was found, his family said. The father and son were planning on spending Father's Day together. Allen's family is seeking to have his body returned to the US to undergo an autopsy back home.

Joseph Allen, 55, of Avenel, New Jersey.

Leyla Cox, 53

Where she's from:

New York City

When and where she died:

She died June 10 in her hotel room at the Excellence Resorts in Punta Cana.

The circumstances:

The hotel gave the cause of death as heart attack, citing a forensics report. CNN has not independently confirmed the contents of the report. Cox's son expressed doubts over the hotel's claims about his mother's cause of death, saying he did not believe she died from "natural causes."

"I truly believe if she was anywhere else in the world besides the Dominican Republic she'd be alive right now," Will Cox said.

Leyla Cox, 53, of New York City.

Nathaniel Holmes, 63, and Cynthia Day, 49

Where they're from:

Maryland

When and where they died.

They were found dead on May 30 at the Grand Bahia Principe in La Romana.

The circumstances:

They missed their scheduled checkout time at the hotel. When hotel employees checked on them, they were dead, police said. Both Holmes and Day had internal bleeding, including in their pancreases, according to Dominican authorities. Holmes had an enlarged heart and cirrhosis of the liver -- both signs of significant pre-existing disease, the Dominican authorities said, and Day also had fluid in her brain. Both also had fluid in their lungs, Attorney General Jean Alain Rodriguez Sanchez's office said in a statement. Authorities said they won't provide more details on the cause of death until toxicology results are completed.

Nathaniel Holmes, 63, and Cynthia Day, 49.

Miranda Schaup-Werner, 41

Where she's from:

Pennsylvania

When and where she died:

She died on May 25, shortly after checking into her room at the Bahia Principe resort in La Romana , the same hotel where Holmes and Day died.

The circumstances:

Schaup-Werner was celebrating a wedding anniversary with her husband, Dan Werner. She suddenly fell ill after having a drink from the minibar, family spokesman Jay McDonald told CNN affiliate WFMZ. Shortly afterward, she collapsed and died. A preliminary autopsy cited by the Attorney General's Office of the Dominican Republic showed that she suffered a heart attack, pulmonary edema and respiratory failure. The death remains under investigation and toxicology results are pending.

Schaup-Werner of Whitehall township, Pennsylvania

John Corcoran

Where he's from:

Unknown

Where and when he died:

A statement from Corcoran's sister, "Shark Tank" star Barbara Corcoran, said that he died at the end of April in his hotel room.

The circumstances:

Corcoran's sister said in the statement that he died of apparent natural causes. "He loved and frequently visited the Dominican Republic," his sister said.

Robert Wallace, 67

Where he's from:

California

Where and when he died:

Wallace died on April 12 after becoming ill at the Hard Rock Hotel & Casino in Punta Cana, relatives told CNN affiliate KTXL

The circumstances:

Wallace was in the country with more than two dozen members of his family for a wedding. His son-in-law, Tommy Tickenhoff, told the station that Wallace became sick after drinking scotch from a minibar.

Robert Wallace

David Harrison, 45

Where he's from:

Maryland

Where and when he died:

Harrison's wife, Dawn McCoy, said Harrison died at the Hard Rock Hotel & Casino in Punta Cana in July 2018.

The circumstances:

Harrison and McCoy were celebrating an anniversary. He said he wasn't feeling well when he returned from a snorkeling excursion, McCoy said. The next morning, he was sweating and unable to get up before he died. The cause of death was listed as a heart attack and pulmonary edema by local authorities.

Yvette Monique Sport

Where she's from:

Pennsylvania

Where and when she died:

Sport died in June 2018 at the Bahia Principe in Punta Cana, her sister Felecia Nieves told CNN.

The circumstances:

Sport was on her first vacation in eight years and was traveling with a group of friends. After having drinks with her fiance, Nieves said, Sport took a shower and went to bed. She also had a drink from the minibar. Nieves said her fiance heard her make "a gurgling sound" in her sleep, and the next morning he discovered that she was dead. The US State Department confirmed the death, and the family is still awaiting toxicology reports.