SAN FRANCISCO (CBS SF) – A San Francisco man died while running a race on Mt. Diablo on Sunday, according to the Contra Costa County coroner’s office.

Rene Brunet, 63, was participating in the Mt. Diablo Trail Run when he died, a deputy coroner said.

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The race began at 8:30 a.m. and participants can run an 8-, 25- or 50-kilometer race.

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A cause of death for Brunet has not yet been determined, the deputy said.

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