Two US police officers will not face charges for shooting dead Stephon Clark, an unarmed black man, in California last March, prosecutors say.

The shooting victim, aged 22, was shot at least seven times in his grandmother's backyard in Sacramento.

According to the district attorney, the officers, who were investigating nearby break-ins, did not commit a crime.

The death sparked protests and fuelled national anger over police use of force, particularly against black men.