The Navy is investigating the death of a SEAL candidate who finished 'Hell Week'

One Navy SEAL candidate is dead and another is recovering after completing "Hell Week," a grueling test early in the forces' training program.

Kyle Mullen, a 24-year-old man from Manalapan, N.J., was pronounced dead at Sharp Coronado Hospital in Coronado, Calif., the Navy said in a series of statements released over the weekend.

An investigation into his cause of death is in progress, according to officials.

The second candidate, whose name has not been released, was in stable condition at Naval Medical Center San Diego as of Saturday.

Both candidates had completed Hell Week — an assessment during the first phase of Basic Underwater Demolition SEAL (BUD/S) training — hours before reporting symptoms and receiving emergency care, the Navy said. The statement did not specify what those symptoms were.

"We extend our deepest sympathies to Seaman Mullen's family for their loss," Rear Adm. H.W. Howard III said in one of the statements. "We are extending every form of support we can to the Mullen family and Kyle's BUD/S classmates."

The BUD/S training is an early phase of the SEALs' selection process that's known as Hell Week because of its intensity. Over the span of 5 1/2 days, candidates survive on no more than four hours of sleep, while undergoing a series of tests that involve running, swimming and other activities that test physical endurance and mental "toughness" and pain, according to the Navy SEAL website. Only around 25% of candidates make it through the Hell Week to continue on with their training.

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