The body of a woman believed to be a 50-year-old hiker who went missing on a trail in San Diego after separating from her group during a heat wave on Sunday was found just short of a populated area, authorities said.

The body of an Asian woman, believed to be Diem Le Nguyen, was discovered off a trail around 9:15 a.m. Monday during a helicopter search of Black Mountain, San Diego Police Lt. Daniel Meyer told reporters during a news conference near the search area.

"She was a quarter-mile away from a population, from reaching a street," Meyer said. "She nearly made it out."

A hat Nguyen was believed to be wearing at the time of her disappearance was also found shortly before search teams spotted the body, Meyer said. 

HIKER LOST FOR 10 DAYS FOUND ALIVE IN NORTHERN CALIFORNIA MOUNTAINS

Diem Le Nguyen on hike

Police said Diem Le Nguyen appeared in this photo taken on the Sunday before she went missing. (San Diego Police Department)

Nguyen was hiking on Nighthawk Trail on Black Mountain with a group of about 100 people, which included family and friends, when the group stopped halfway up the trail at around 8 a.m., police said. 

Nighthawk Trailhead sign

Diem Le Nguyen disappeared on the Nighthawk Trail after separating from her group to continue on the trail alone, authorities said. (FOX5 San Diego KSWB)

The group was participating in an annual fundraiser for the Build a School Foundation, according to FOX5 San Diego.

Nguyen left the group on her own and continued toward the peak alone, according to police.

Diem Le Nguyen

Diem Le Nguyen, 50, was reported missing Sunday after disappearing during a hike on Black Mountain's Nighthawk Trail in San Diego. (San Diego Police Department)

Nguyen made a "phone call of distress" to her family around 10 a.m., stating she was very hot and needed water, Meyer told reporters. It was the last time anyone heard from Nguyen.

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Due to the phone call and excessive heat in the mountains, Meyer said that search and rescue crews, which included helicopters, dogs, drones and ground teams, were immediately deployed to find Nguyen.

search and rescue base

Search and rescue teams are searching for missing hiker Diem Le Nguyen near the Nighthawk Trail on Black Mountain in San Diego. (FOX5 San Diego KSWB)

Officials in California warned of high temperatures affecting inland San Diego over the weekend, and the National Weather Service issued an excessive heat advisory for parts of Southern California through Sunday.

"Obviously it’s a very painful moment for the family and friends," Meyer said. "It’s really important for the community to come together and support this family as they go through this traumatic time."

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Meyer said a death investigation will be conducted by the Medical Examiner’s Office, which will confirm the identity of the body.