LATEST: Washington - The US Capitol building has ended a lockdown, which saw police barring people from entering.The Senate sergeant at arms issued a lockdown alert for the building and visitor centre, saying police activity has been reported. Capitol office buildings are open.Capitol police said they were searching for an individual but offered no details. One officer outside the Capitol said police had responded to sketchy reports of woman who may have had a gun. (AP) Dallas – The suspect in the Dallas police sniper attacks told negotiators that he wanted to kill white people, especially white officers, after a recent spate of US police-involved shootings of black men, the city's police chief said on Friday.Chief David Brown appealed for unity in the wake of the attacks, which left five police dead and nine wounded – seven of them cops – saying: "This must stop – this divisiveness between our police and our citizens."The suspect was killed by an explosive device detonated by police during a tense standoff, after Thursday night's shooting rampage during a protest over the fatal police shootings of two black men this week in Louisiana and Minnesota, Brown said.