Washington (AFP) – US President Joe Biden offered a potent condemnation of racist extremism Sunday after a murderous rampage in Buffalo, and he called for citizens to end the hate that remains a “stain on the soul of America.” “A lone gunman, armed with weapons of war and a hateful soul, shot and killed 10 innocent people in cold blood at a grocery store on Saturday afternoon” in western New York state, Biden said in Washington at a service for fallen US police officers. “We must all work together to address the hate that remains a stain on the soul of America,” the president said. US authorit…