Michael Brown shooting: Protests as police kill armed man
19 August 2014 Last updated at 22:39 BST
The police killing of a second black St Louis-area man in 11 days has threatened to further enflame tensions.
On Tuesday, police officers shot dead a man who brandished a knife at them, St Louis Police Chief Sam Dotson said.
The 9 August police shooting of Michael Brown, 18, has sparked days of violent protests in the town of Ferguson, prompting a heavy police crackdown.
Aleem Maqbool reports from Ferguson.