A 45-year-old mother was aboard the REACH Air Medical Services helicopter when it went down near Pebbly Beach, about a mile from Avalon, according to her family and the Los Angeles County Fire Department.

Her family said Catalina Hernandez had eaten something that caused the allergic reaction and was being airlifted for treatment when the crash happened, according to NBC.

Her son was also aboard the helicopter and was injured in the crash, a family member said.

He was being treated at a hospital, NBC reported.

The helicopter had five people aboard when the crash was reported shortly after 7:50 p.m. near the helipad at Pebbly Beach, according to the Los Angeles County Fire Department.

Two people were killed and two others were injured. Hernandez remained unaccounted for hours after the crash.

Authorities had not determined what caused the helicopter to go down.

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