Oxfam Australia said it was deeply saddened and shocked at the passing of the participant on Friday evening.
The person’s next of kin has been notified, Oxfam said in a statement.
No other details were immediately available.
Oxfam said the event, which began on Friday morning, was continuing.
There are 750 teams of four people taking part in the Trailwalker endurance event, which sees participants walk 100km through rugged Victorian bush within 48 hours. An Ambulance Victoria spokesman says a man in his late 40s collapsed on the 1000 Steps in the Dandenong Ranges National Park at Ferny Creek about 7.15 (AEST) last night.
He says two off-duty paramedics and another man immediately began CPR until paramedics monitoring the event arrived, but the man died at the scene.
Source: Sky News Australia