Dallas shootings gunman had rifles and bomb-making materials at his home
An Army veteran killed by Dallas police after the sniper killings of five officers amassed a personal arsenal at his home, including bomb-making materials, bulletproof vests, rifles, ammunition and a journal of combat tactics.
The news came as Homeland Security Secretary Jeh Johnson said there appeared to have been one gunman in the Dallas shootings.
The veteran, identified as 25-year-old Micah Johnson, told authorities that he was upset about the police shootings of two black men earlier this week and wanted to exterminate whites, "especially white officers," officials said.
He was killed by a robot-delivered bomb after the shootings, which marked the deadliest day for US law enforcement since the September 11, 2001, terrorist attacks. In all, 12 officers were shot.
In Georgia, Missouri and Tennessee, authorities said gun-wielding civilians also shot officers in individual attacks that came after the two black men died at the hands of police in Louisiana and Minnesota. Two officers were wounded, one critically.
Johnson was a private first class from the Dallas suburb of Mesquite who specialised in carpentry and masonry. He served in the Army Reserve for six years starting in 2009 and did one tour in Afghanistan from November 2013 to July 2014.
After the attack, he tried to take refuge in a parking garage and exchanged gunfire with police, Police Chief David Brown said.
The suspect described his motive during negotiations and said he acted alone and was not affiliated with any groups, Mr Brown said.
Johnson was black. Law enforcement officials did not immediately disclose the race of the dead officers.