Former San Francisco 49er Colin Kaepernick reveals why he became an activist

SAN FRANCISCO (KGO) -- For the first time, Colin Kaepernick is revealing the incident that inspired his quest for social justice and civil rights.

In an article in the latest edition of Paper Magazine, Kaepernick says the 2015 shooting death of Mario Woods in San Francisco was the catalyst for his activism.

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The former 49er told the magazine he was deeply affected by the incident, in which Woods was shot 21 times.

Kaepernick began his silent protest nine months later, taking a knee during the national anthem.

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