Violent protests over the police custody death of an African-American man in Minneapolis spread to dozens of cities across the United States over the weekend despite the arrest of an officer involved in the incident. Shots were fired at police officers in Minneapolis, Minnesota, as they tried clear demonstrators who gathered in defiance of an 8pm curfew imposed after consecutive nights of violent demonstrations. The incident occurred in the Fifth Precinct of the city, but protesters gathered in several parts of the city, including the Lake Street neighbourhood, where a police station was burned the night before. There were scattered small fires on Friday and more shops were broken into. The Pentagon took the rare step of ordering the army to put military police units on stand-by to deploy to Minneapolis, sources told Associated Press. The move followed President Donald Trump's threat to send troops to the city if arson and looting continued. Crowds gathered around the White House on Friday to protest the death of George Floyd and the president's response. On Thursday, as violence broke out in Minneapolis, Mr Trump tweeted: “When the looting starts, the shooting starts.” He later said his comments had been misconstrued. “Frankly it means when there’s looting, people get shot and they die,” he said Protesters threw bottles and other objects at officers wearing antii-riot gear behind barricades around the White House. Pepper spray was used to disperse the crowd, and police and protesters wrestled over the barricades. US President Donald Trump accused the White House protesters of being "professionally managed" and only on the streets "to cause trouble". He did not provide evidence to support the comments, which he made in the early hours of Saturday on Twitter. The renewed protests on Friday came after Minneapolis police officer Derek Chauvin was charged with third-degree murder and second-degree manslaughter in connection with the death of Floyd, 46, who was arrested on Monday on suspicion of using a counterfeit banknote. Video footage of the arrest showed Mr Chauvin pinning Floyd's neck down with his knee for several minutes, despite the man's pleas that he could not breathe. In Phoenix, Denver, Las Vegas, Los Angeles and other cities, thousands of protesters carried signs that said: “He said I can’t breathe. Justice for George.” They chanted “No justice, no peace” and “Say his name. George Floyd.” A peaceful demonstration in New York City spiralled into chaos as night fell, as protesters clashed with officers, destroyed police vehicles and set fires. In Brooklyn, activists who had marched from Manhattan chanted insults at officers lined up outside the Barclays Centre sports arena and pelted them with water bottles. Video posted to social media showed officers using batons and shoving protesters down as they took people into custody and cleared streets. Demonstrators rocked a police van, set it on fire, scrawled graffiti across its burnt hulk and set it on fire a second time as officers retreated from the area. Blocks away, protesters used a club to batter another police vehicle. Police loaded handcuffed protesters on to city buses lined up on Atlantic Avenue, shutting down a major thoroughfare. The police department said several officers were injured. “We have a long night ahead of us in Brooklyn,” Mayor Bill de Blasio tweeted. “Our sole focus is de-escalating this situation and getting people home safe. There will be a full review of what happened tonight. We don’t ever want to see another night like this.” The governor of Georgia declared a state of emergency on Saturday and mobilised 500 National Guardsmen "to protect people and property in Atlanta" after protests in the state capital turned violent on Friday. Demonstrators smashed police cars and vandalised the CNN headquarters, spray-painting on the news channel's logo outside and breaking windows. Some protesters set fire to a police car, shot at officers with air pistols and threw bricks, bottles and knives. At least three officers were hurt and there were arrests, a police spokesman said. More than 1,000 protesters marched to the state capitol building from the Centennial Olympic Park, blocking traffic and an interstate motorway. The violence came despite pleas for non-violence from the city's mayor and from Bernice King, the youngest daughter of civil rights leader Martin Luther King Jr. "The only way we get what we really want is through non-violence," Ms King said. "Let's do this the non-violent way to deal with the evil of our time." One person was killed in Detroit, Michigan, just before midnight after someone in an SUV fired shots into a crowd of protesters near the city’s Greektown entertainment district, police said. In Portland, Oregon, protesters broke into police headquarters on Friday night and lit a fire inside. In Virginia's capital, a police car was set on fire outside Richmond police headquarters, and a city transit spokeswoman said a bus set ablaze was “a total loss”, news outlets reported. Protests elsewhere were more peaceful. In Colorado, a second day of protests passed peacefully as hundreds marched through central Denver to demand justice for Floyd. Denver police had used tear gas and rubber bullets to disperse crowds on Thursday night, after parked cars were vandalised. Several people were arrested. In Houston, Texas, hundreds gathered at City Hall for a protest organised by the group Black Lives Matter. The crowd spilled on to Interstate 45's entrance ramp near the central part of the city and raised slogans, "I can't breathe," and "No justice, no peace." Hundreds of marchers temporarily shut down a five-lane section of motorway in San Jose, the main city in California's Silicon Valley. "We are out here because we, as a generation, realise things have to change," said Paul Selman, a black protester in Minneapolis. "We need peace." "Our parents and grandparents are tired of seeing their kids die all of the time, so we have to take it upon ourselves to make a better future," he told Reuters.