A woman fell to her death and a teenager was seriously injured at a popular southern California hiking trail during the woman's attempt to help the girl, who had slipped, authorities said.

Sarah Louise Crocker, 48, was hiking with four teenagers Thursday morning at Three Sisters Falls in the Cleveland National Forest, an unincorporated area of Descanso, according to the San Diego County Sheriff's Department.

The San Diego County Medical Examiner's Office described the teenagers traveling with Crocker, who was from Ladera Ranch, California, as "family and family friends" in a news release.

The group was hiking along a ledge and were within the middle pool of the falls when one of the teenagers slipped, according to the medical examiner's office and sheriff's department.

In an attempt to keep the girl from going over the ledge, Crocker reached out to the girl and lost her footing, the medical examiner's office said.

They both fell over the waterfall's edge and landed in the bottom-most pool of water, according to the medical examiner.

Crocker and the teenager "suffered severe injuries," the sheriff's department said.

Several witnesses attempted to render aid to both victims. Responding rescuers could not revive Crocker and pronounced her dead at the scene, the medical examiner reported.

Crocker died of multiple blunt force injuries and drowning, and the medical examiner ruled her death as an accident.

The injured teenager was taken via helicopter to a hospital for treatment of severe but non-life-threatening injuries, according to the sheriff's department.

Three Sisters Falls in east San Diego County is described as an "often crowded, yet challenging" hiking area comprising three large waterfalls between tall and rocky mountains, according to the US Forest Service.

"The sheriff's department does respond to multiple injuries and rescues in that area every year," San Diego County Sheriff's Department spokesperson Lt. Jeff Ford said in a statement to CNN.

"We have had fatal accidents out there in the past, but fatalities are a rare occurrence," Ford said.

The "vast majority" of incidents occur during the summer months and are related to heat exhaustion or other minor injuries, he added.