Washington, May 30 : The White House has been put under a lockdown as protests over the death of an unarmed black man in custody reached Washington on the fourth day of nationwide demonstrations against the incident in Minneapolis. The nationwide protests were against the death of 46-year-old African-American George Floyd on Monday after being detained on suspicion of trying to use a fake $20 bill at a supermarket, reports Efe news. In videos recorded by passers-by, Derek Chauvin, a white police officer, is seen holding Floyd down with a knee on his neck although the victim repeatedly pleaded, "I can't breathe", and "please, I can't breathe". On Friday, Chauvin was arrested and charged with three-degree murder and manslaughter.. In Washington D.C. on Friday, hundreds of protesters gathered in Lafayette Park just outside the White House, chanting "No justice, no peace", reports Xinhua news agency. Video footages showed a young man climbing on the railing of the Freedman Bank building, situated opposite the President's residence and housing the Office of Foreign Assets and other government offices, to paint graffiti against President Donald Trump amid applause from the crowd. Some demonstrators also tore down barricades in front of the White House on more than one occasion, resulting in moments of tension, while some other demonstrators clashed with Secret Service personnel, witnesses said. The doors to the White House briefing room have also been locked and Secret Service officers were not letting anyone off White House grounds, local media reported. "Secret Service personnel are currently assisting other law enforcement agencies during a demonstration in Lafayette Park. In the interest of public safety we encourage all to remain peaceful," the Secret Service tweeted. Curfew has been imposed until Sunday in the twin cities of Minneapolis and St Paul Â? separated by the Mississippi river Â? by their respective mayors in an attempt to control the protests and violence that the region has witnessed during the last three days. The curfew was imposed on Friday after another night of disturbances, with incidents of looting and a police station being set on fire in Minneapolis. Meanwhile in downtown Atlanta, near the headquarters of the CNN television network, groups of protesters smashed store windows, to which the riot police responded with tear gas, according to television broadcasts. Some of the protesters threw rocks at the CNN building and several police vehicles parked outside the premises were also targeted with projectiles, with at least two of them set on fire. In New York, hundreds took to the streets on Friday for the second consecutive day. The first protest was held in Manhattan's Foley Square, although the most violent actions were recorded in Brooklyn, with three epicentres Â? Prospect Heights at the Barclays Center, Clinton Hill, and in Fort Greene Park where protesters set fire to an empty police van. In Los Angeles, protesters marched shouting slogans such as "I can't breathe" amid heavy police presence. A police officer was attacked in the street and squad cars' windows were smashed by protesters, while several people were detained for allegedly throwing objects at officers and damaging police cars. A group of about 100 protesters reportedly blocked a major north-south freeway in downtown Los Angeles. Protests over Floyd's death continued on Friday night in Minneapolis and a number of other cities, including Boston, Charlotte, Houston, Chicago, Denver, Phoenix and Memphis, local media reported, adding that more demonstrations were expected to take place across the country through the weekend. /IANS