PACIFIC PALISADES—A man was hiking the Santa Monica Mountains when he collapsed and died on Sunday, June 24.

The hiker has been identified as John Duncan, 52, of Porter Ranch. The Los Angeles Fire Department tweeted at around 3:45 p.m.:

Adult M collapsed pulseless and non-breathing while hiking on remote East Topanga Fire Road in/near Topanga State Park; Witness CPR continued by LAFD ground responders, who await LAFD helicopter to land nearby and/or hoist and transport patient in critical condition;

Paramedics were called to the scene and performed CPR on Duncan before he was pronounced dead on the scene. An autopsy has not been completed to determine Duncan’s precise cause of death.