In suburban St. Louis, a motorist shot an officer at least once as the officer walked back to his auto during a traffic stop, police said.
And then, like clockwork in a new deranged norm, came another evening, another night of tragedy.
Five police personnel were killed and seven others injured as two snipers opened fire at them during a protest against police shootings of two African-American men in Louisiana and Minnesota, in downtown Dallas Thursday night. Authorities said it was the work of at least one sniper.
It was a devastating climax to three horrific days that Americans are struggling to understand.
In suburban St. Louis, a motorist shot an officer at least once as the officer walked back to his vehicle during a traffic stop, police said.
The man believed to be responsible for the deadly police ambush in Dallas has been identified by law enforcement officials as 25-year-old Micah Johnson, multiple media outlets report. It's not clear where the 12th officer was shot.
Texas Governor Greg Abbott also said he had "no information about any co-conspirators".
A map will be posted online showing an area where people should avoid on Friday, he said.
"In the end", he wrote, "evil always fails".
Reports of more police shootings are coming out of the United States, but local police are not directly linking the violence to attacks in Dallas.
Johnson was black. Law enforcement officials did not immediately disclose the race of the dead officers.
Mayor Mike Rawlings told reporters on Friday morning that Dallas this year has the fewest police officer-related shootings of "any large city in America". Two civilians were also wounded.
Rawlings said that racial tensions continue to divide the city, the state and the nation.
"At this time, there appears to have been one gunman, with no known links to or inspiration from any global terrorist organization", U.S. Homeland Security Secretary Jeh Johnson told reporters in NY.
"I think this is an anomaly", said Brian Hart, the president of Black-I Robotics, which makes ground robots for the government. "The presence of video documentation of the incidents calls attention to strife that had previously existed only in agonizing private memories". Police said he told them what had prompted the attack.
Dallas Police Chief David O. Brown said that Johnson, who was black, had told negotiators before he was killed that he was upset with the fatal shootings earlier in the week of black men by police officers in Louisiana and Minnesota.
Both killings were captured on video and posted online. "There's just a really scary sense of humanity right now", she said. "I don't know what's going on". You and I know what we must do and I don't mean marching, making a lot of noise, or attending conventions. Many have wondered if he can sue.
King County Sheriff John Urquhart said the officers in Dallas did what they had to do to minimize further casualties. "I'm a husband", he said. The officers shot in Dallas were working a march of the Black Lives Matter movement.
Three other people were detained by police, but authorities have not publicly linked them to the shootings.
The Dallas Police Department is known to be at the forefront of those efforts.
He was the first officer killed in the line of duty since Dallas Area Rapid Transit formed a police department in 1989, DART said on its website.