Dallas police end search for suspicious person in headquarters' parking lot

Dallas police officers searched for hours for a suspicious person in the parking garage at their headquarters Saturday, the department tweeted. The search yielded no suspects or strange items,Nike Ninja the department said. Officers and police dogs searched the three-story facility for several hours. It was unclear who reported the suspicious person. The search came as visitors were dropping by the headquarters to pay tribute at a memorial for five police officers who were killed by a gunman Thursday night after a protest march. Dallas police had tightened security throughout the city because of an anonymous threat, spokeswoman Monica Cordova said earlier without elaborating. The search also came as Dallas police defended their use of bomb-carrying robot that killed Micah Xavier Johnson, the man who gunned down four Dallas police officers and one transit police officer this week. The police department said it used the robot as a last resort. Negotiations had failed and the gunman was still shooting at them, so police used C4 with a detonation cord mounted on a Remotec F-5 robot. The explosive weighed about one pound, police said. Ongoing investigation Dallas detectives are piecing together a picture of Johnson to determine whether he acted alone in his ambush of police or had allies in preparing for the shooting that killed the five officers. Authorities have said they believe Johnson was the sole gunman during the Black Lives Matter protest Thursday in Dallas. What is unclear is whether the 25-year-old army veteran, whom some people described as a loner, conspired with others or how long he had planned an attack. Seven other officers were wounded in the ambush. Two civilians were also hurt, the Dallas mayor's office said. The shootings came amid a protest over the fatal police shootings of two black men in Louisiana and Minnesota this week. Similar protests -- mostly peaceful -- were held Friday in dozens of cities across the United States, and more are planned for Saturday. Obama: Americans are united Officers shot during Dallas protest Photos: Officers shot during Dallas protest President Barack Obama said Saturday the reaction of the majority of Americans, protesters and police to the week's trio of tragedies showed a nation remarkably unified despite some views it is polarized on racial issues. Nike Tn Americans of all stripes were outraged a "deranged" individual killed the five officers in Dallas just as American have deep concerns about police shootings in Louisiana and Minnesota, said the President, speaking in Warsaw, Poland, where he was attending a NATO conference. "There is sorrow, there is anger and there is confusion about next steps but there is unity in that this is not how we want our communities to operate, this is not who we want to be as Americans," Obama said For the President, that was grounds for optimism that the nation would move forward in a constructive way. He noted the scenes around the country were not akin to the polarized 1960s. "You're not seeing riots and you're not seeing police going after people who are protesting peacefully," the President said. "As tough, as hard, as depressing as the loss of life was this week, we have a foundation to build on. We just have to have confidence that we can build on the better angels of our nature." Who was Micah Xavier Johnson? Johnson had no criminal record or known terror ties, a law enforcement official said. He served in the U.S. Army Reserve from March 2009 to April 2015, training as a carpentry and masonry specialist, according to Pentagon records. Johnson was deployed for about seven months in Afghanistan, from late 2013, and received an honorable discharge. Johnson had at least two weapons with him -- a rifle and a handgun, two law enforcement officials have said. One of the officials, familiar with the latest information from the Dallas police investigation, said the rifle was an SKS semi-automatic. The other official said Johnson legally bought multiple firearms in the past. Johnson's last known employer was Jeppie Carnegie, who owns a home health care facility in Dallas. He told CNN he hired Johnson in January 2015. Carnegie said a background check showed no past criminal activity. Johnson's client was his own younger brother and he supported his sibling's home living, Carnegie said. The Touch of Kindness owner told CNN he had infrequent interaction with Johnson,Nike Tn but always as professionals.