PHOENIX (AP) — Klee Benally, a Navajo man who advocated on behalf of Indigenous people and environmental causes, has died, his sister said. He was 48 years old.

Benally died Saturday at a Phoenix hospital, Jeneda Benally said. His cause of death was not disclosed.

Klee Benally was among the most vocal opponents of snowmaking at Arizona Snowbowl ski resort in Flagstaff. At least 13 tribes consider the mountain on public land to be sacred.

He protested police violence and racial profiling and was among activists who gathered outside metro Phoenix’s NFL stadium in 2014 to denounce the offensive team name previously used by the franchise from Washington, D.C.

Benally advocated for the cleanup of abandoned mines, where uranium ore was extracted from the Navajo Nation over decades to support U.S. nuclear activities during the Cold War.

He also spoke out against an ordinance that, in a bid to address the problem of homelessness, had banned camping on public property in Flagstaff.

“There is no compassionate way to enforce the anti-camping ordinance,” Benally said in 2018 when officials declined to alter the 2005 ordinance. “Life is already hard enough for our unsheltered relatives on the streets.”

Benally was also a guitarist, and played with his sister and brother in the Native American punk rock band Blackfire.