Three sailors in the United States Navy have died in the span of nine days onboard the same aircraft carrier and it remains unclear how. The Navy for its part has been tight-lipped about the circumstances of their deaths, but it has supported an investigation to determine how they died.

On Tuesday, CNN reported that the Naval Criminal Investigative Service together with local law enforcement has been investigating the deaths of three sailors aboard the USS George Washington, a nuclear-powered aircraft carrier that has been undergoing repairs and upgrades.

The Navy has not disclosed the name of one of the sailors, but the first death was reported last Friday when a sailor was found unresponsive aboard the George Washington. The two other sailors, Retail Services Specialist 3rd Class Mikail Sharp and Interior Communications Electrician 3rd Class Natasha Huffman, were found dead off-base at separate locations on April 9 and April 10. A spokesman for the service said that the deaths did not appear to be connected beyond the deceased serving on the same ship.

Much about the case remains unclear. The Navy has not yet identified where the two who died off-base were discovered and it has not shared the cause of death for any of the sailors to date. The USS George Washington is assigned to naval forces stationed at Norfolk, Virginia.

Huffman’s mother, Kathleen Krull, wrote on Facebook that arrangements were being made with the Navy for a funeral. On Tuesday, Sharp was laid to rest at a funeral ceremony in Norfolk, according to an online obituary.