Press TV - Hundreds of outraged US protesters have clashed with the Secret Service and police outside the White House for the second successive day over the police brutal killing of an African American earlier this week.

The unrest over George Floyd�s death came to President Donald Trump�s doorstep as demonstrators circled the White House grounds on Saturday, chanting �I can�t breathe� and �Black Lives Matter.�

Earlier in the day, Trump threatened that if the demonstrators who had gathered the night before in Lafayette Square, across from the White House, had breached the fence, �they would have been greeted with the most vicious dogs, and most ominous weapons, I have ever seen.�

On Saturday, some protesters stayed near the president�s residence, while others marched through the streets chanting, �No justice and no peace� and �Say his name: George Floyd.�

Armored Secret Service, along with District of Columbia police and park police Saturday formed a barricade in front of the protesters as Trump returned to the White House from a trip to Florida.

Although some demonstrators overcame the barriers and entered the park in front of the White House, police wielding shields, batons and pepper spray drove them out.

Protesters caused serious damage to several Secret Service vehicles and threw themselves against officers� riot shields, according to the Washington Post.

Curfews have been announced in several US cities as protesters took to the streets to vent outrage following video footage showing how Floyd died after a white Minneapolis police officer pressed his knee into his neck as he begged for air.

The video showed ex-Minneapolis police officer Derek Chauvin, who is white, kneeling on Floyd�s neck for nearly 9 minutes as Floyd cried for his mother and said he couldn�t breathe.

Mass protests have been held during the past four days with several cities being the scene of chaos.

Curfews went into effect on Saturday evening in many cities including Cleveland, Seattle, Philadelphia, Denver, Atlanta, Los Angeles, Chicago and Minneapolis where 46-year-old Floyd died on Monday.

However, many demonstrators remained defiant with law enforcement officers responding with a show of force in an attempt to disperse otherwise peaceful crowds.

�Even though it�s past curfew, we�re still out here because they�re paying attention to us,� said 18-year-old Hoonday Ahmed in Minneapolis. �That�s why we�re out there. We�re trying to send a message.�

In Minneapolis, the governor "fully mobilized" the Minnesota National Guard on Saturday for the first time since World War Two after four nights of protests.

Thousands of Chicago protesters marched through the Windy City's downtown on Saturday after more than 100 protesters were arrested Friday night.

In Los Angeles, protests continued on Saturday as buses were overtaken and several police cars were set on fire.

In Denver, Mayor Michael Hancock, who announced he was enacting a curfew on Saturday, said 34 people had been arrested in the past two nights.

Philadelphia demonstrators marched in streets in a protest that resulted in many fires.