DRY TORTUGAS NATIONAL PARK, (AP) — A 74-year-old woman died while snorkeling in the Dry Tortugas National Park, which is in the Gulf of Mexico west of Key West, Florida.

Monroe County Sheriff’s officials say Carol Murrell Maillet of Seattle, Washington, was snorkeling along the fort wall by the beach Thursday afternoon when family members heard her screaming.

Some nearby people helped bring her to the beach and began CPR. She was then airlifted to the Lower Keys Medical Center on Stock Island in the Florida Keys.

Officials say she was not on a guided snorkeling trip. The incident remains under investigation, but foul play is not believed to be a factor.