DALLAS • Thousands of protesters have marched in cities across the United States, a day after a gunman shot dead five police officers during a protest in Texas.
President Barack Obama said he will cut short a foreign trip as the shooting rampage by the black army veteran, who said he wanted to kill white policemen, triggered urgent calls to mend troubled race relations in the country.
Police said the attack in Dallas on Thursday during a peaceful rally against police brutality was carried out alone by Micah Johnson, 25, instead of multiple shooters as they initially thought. Johnson had served as a US Army reservist for six years.
While the White House ruled out any link between him and known "terrorist organisations", Johnson's Facebook page ties him to several radical black movements listed as hate groups. A search of his home just outside Dallas found bomb-making materials, rifles, ammunition and a personal journal of combat tactics, though he had no previous criminal history, the police said.
Johnson shot a total of 12 people during his attack - seven other police officers and two civilians were wounded.
It's on all of us to stand up, to speak out about disparities in our criminal justice system - just as it's on all of us to stand up for the police who protect us in our communities every day.
US VICE-PRESIDENT JOE BIDEN, on coming together to fight injustice. Dallas shooting
Before he was killed by police following a long stand-off, he told negotiators that he wanted to kill white policemen in retaliation for the fatal police shootings in Louisiana and Minnesota. Two African-American men, Mr Alton Sterling in Louisiana and Mr Philando Castile in Minnesota, were shot dead by police last week. Video footage of their final moments went viral online, triggering racial tensions and anger over police use of force against black people.
In the protests held from Friday night until yesterday, many remembered the officers slain in Dallas even as anger simmered over the deaths of black men at the hands of the police.
Vast crowds marched in cities including Houston, New Orleans, Detroit, Baltimore, Philadelphia and San Francisco. One of the largest was in Atlanta, where protesters blocked a major road.
In Phoenix, police in riot gear used pepper spray to disperse a large crowd that hurled rocks and threatened to block a highway. At least one person was arrested.
And in Rochester, New York, police chief Michael Ciminelli said that 74 people were arrested for blocking a street in what appeared to be a peaceful sit-in protest.
"As Americans, we are wounded by all of these deaths," Vice-President Joe Biden said yesterday. "It's on all of us to stand up, to speak out about disparities in our criminal justice system - just as it's on all of us to stand up for the police who protect us in our communities every day."
Addressing a prayer service honouring the fallen officers, Dallas Mayor Mike Rawlings urged Americans to "step up" to heal the country's racial wounds. He echoed Mr Obama's message that black lives matter - and so do "blue" lives, those of police officers.
Mr Obama, who ordered flags on government buildings lowered to half-mast for five days, said that there was "no possible justification" for violence against the police. The President commented on the attacks from Warsaw, where he was attending a Nato summit. The White House said he would return home today, one day ahead of schedule, and visit Dallas early this week.
Following Thursday's attack, the police in Cleveland said they were tightening security plans for next week's Republican National Convention.
Other police departments, including in New York, Chicago and St Louis, required officers to patrol in pairs rather than alone as a safety precaution.
AGENCE FRANCE-PRESSE, REUTERS