WATCH LIVE: Thousands protest against police violence in Atlanta

Thousands of people took to the streets in U.S. cities on Friday to denounce the fatal police shootings of two black men this week, marching the day after a gunman killed five police officers watching over a similar demonstration in Dallas.

Protesters clogged roadways in New York City, Atlanta and Philadelphia on Friday evening, and events also were planned for San Francisco and Phoenix. Local media reports did not indicate any immediate instances of major clashes or injuries.

Thousands marched in Atlanta in what appeared to be the largest demonstration, chanting and waving signs demanding justice, video posted to social media showed. Footage from local broadcasters showed the massive crowd facing off with dozens of police vehicles that were stopped on a local interstate highway.

Atlanta Mayor Kasim Reed tweeted that the rally was largely peaceful, though about 10 people had been arrested.

Friday was the second day of widespread demonstrations against use of force by police in the wake of the fatal shootings of 32-year-old Philando Castile near St. Paul, Minnesota and 37-year-old Alton Sterling in Baton Rouge, Louisiana.

Castile was killed by police during a traffic stop late on Wednesday, and his girlfriend posted live video on the Internet of the bloody scene minutes afterward.

Sterling was killed during an altercation outside a convenience store with two white police officers. Graphic video of that incident caused an outcry on social media.

The two shootings stoked racial tensions that have flared repeatedly across the country following the 2014 killing of Michael Brown, an unarmed black teen, by a white police officer in Ferguson, Missouri.

Thursday's demonstrations were largely peaceful until gunfire erupted at a Dallas rally that was winding down.

Authorities said 25-year-old Micah Johnson, a black U.S. military veteran of the Afghan war who said he wanted to "kill white people," launched a sniper attack that killed five police officers and wounded nine other people.

Police killed the gunman with a bomb-carrying robot after cornering him in a parking garage, ending an hours-long standoff.

(Editing by Colleen Jenkins and Mary Milliken)

Watch live coverage of the Atlanta march from WSB-TV below.

WXIA-TV is also streaming its coverage, which can be seen here.