Snipers opened fire on police officers in Dallas, killing five officers and injuring six others during protests over the fatal police shootings of black men.
Police had the city on lockdown after a suspect warned that bombs had been planted throughout the city center.
The shootings, which the police called a "terrorist incident", took place as several hundred people marched through the Texan city to protest the fatal shootings this week of two black men by police in Louisiana and Minnesota.
As the rally was winding up, shots rang out around 9:00 pm (0200 GMT Friday), causing panic among the protesters, who scrambled to take cover.
The shootings, which looked set to further strain race relations in the US, stunned the country.
One witness at the rally spoke of "complete pandemonium."
"There was blacks, whites, latinos, everybody. There was a mixed community here protesting. And this just came out of nowhere," Cory Hughes, a brother of the man who turned himself in and was cleared, told CNN.
"I'm still kind of startled, shaken up. As you know being in the front, it's almost like the gunshots were coming at us. It was complete pandemonium... It's bananas."
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