- Investigators believe the Dallas gunman who shot 14 people, including five murdered police officers, originally planned a much larger attack.
On Thursday, five white police officers were shot dead by a black man, Micah Johnson, during a protest rally.
Dallas Police Chief David Brown on Friday said the gunman cited his anger over police killings during his protracted negotiations with police after the shootings.
"As tough, as hard, as depressing as the loss of life this week was, we've got a foundation to build on", he said.
Police in Dallas, Texas, said Saturday they have received a new threat two days after a former US army veteran allegedly killed five officers during an otherwise peaceful Black Lives Matter protest in the city.
Speaking after the match, she said news of the slaying of two black men by police this week, and Johnson's retaliatory attack, was very painful to see.
"For our officers, they were suspects", he said.
Some legal and civil liberties analysts said the unprecedented action threatened to disrupt the established legal order on homicides by law enforcement.
"In the Dallas case, it's obvious that it fits within the umbrella because the individual has made statements to police that he wanted to kill white policemen".
Among those injured were two officers from El Centro College, the school said Sunday night.
Before the cop killer was taken down, he revealed to police that he was bent on killing "white officers" in reaction to recent police shootings of black men elsewhere in the country, but he did not claim allegiance to any political or terrorist organization.
They said they discovered bomb-making materials, ballistic vests, rifles, ammunition and a personal journal detailing combat tactics.
Officials have searched a home Johnson shared with his mother in Mesquite, Texas, just outside of Dallas, but they tell NPR it is unclear how much time Johnson actually spent at that residence and whether he may have other apartments in the area that they haven't yet discovered.
Dallas Mayor Mike Rawlings said that this device can be used in similar situations across the country but only as a last resort.
The Dallas SWAT team has deployed to the downtown police headquarters after what is being called a "credible threat" was received. Police say Kemonte Gilmore flashed a handgun in the video and talked about the slayings of Philando Castile in Minnesota and Alton Sterling in Louisiana. "I have thousands of people".
He followed black militant groups on social media, including one that posted a message Wednesday encouraging violence against police.
Police spokeswoman Sr. Cpl.
A Tennessee man accused of shooting indiscriminately at passing cars and police on a highway told investigators he was angry about police violence against African-Americans, authorities said.
Video from Thursday in Dallas showed protesters marching along a downtown street about half a mile from City Hall when shots erupted and the crowd scattered, seeking cover.