The death of a Navy SEAL candidate is under investigation after 24-year-old Kyle Mullen passed away just hours after completing "Hell Week" training. Toni Yates has the story.

Kyle Mullen, a Navy SEAL candidate, died hours after completing "hell week" training. His mother told ABC News his death could have been prevented.

The last Navy SEAL candidate to die during BUD/S training was 21-year-old Seaman James Lovelace who drowned in a pool during his first week of training in May 2016.

Kyle Mullen, a Navy SEAL candidate, died hours after completing "hell week" training. His mother told ABC News his death could have been prevented.

The Pentagon is asking for time to allow the Navy to investigate the death of 24-year-old Kyle Mullen of Monmouth County, New Jersey, the fourth candidate to die during SEAL selection since 2001.

The training includes a seven-day stretch of little sleep, self-induced hypothermia and brutal physical conditioning known as “Hell Week.” It is here that the majority of SEAL hopefuls quit ...

Hell Week isn’t some inspirational Instagram quote—it’s a prolonged beatdown from Neptune himself, and the only way out is through, one sand-chafed, sleep-deprived, surf-tortured hour at a time.

Before the training program known as BUD/S even begins, trainees go through a five-week pre-training and “indoctrination” process, the Navy SEALS website says.