A white police officer has been cleared in the shooting of Jacob Blake, a black man, in Kenosha, Wisconsin.
District attorney Michael Graveley decided not to charge officer Rusten Sheskey over the incident, which left Mr Blake paralysed after he was shot in the back.
Mr Graveley said the officer had the right to self defence, after officials said there was a knife in the car Mr Blake was trying to get into.
Mr Blake's lawyer said his client was trying to break up a fight between two women and was shot in front of his three sons, aged three, five and eight.
The shooting, which was captured on video, happened during a summer marked with protests over police brutality and racism, with the Black Lives Matter movement coming to the fore.
More than 250 people were arrested in the days the followed the incident, including Kyle Rittenhouse.
The 17-year-old was charged with fatally shooting two people and wounding a third in Kenosha.
Announcing that Mr Sheskey would not be facing charges, Mr Graveley said he "would have to disprove the clear expression of these officers that they had to fire a weapon to defend themselves".
He added: "I do not believe the state... would be able to prove that the privilege of self defence is not available."
Kenosha, which has a similar population to Worcester (around 100,000), is around 60 miles (97km) north of Chicago.
Ahead of the announcement of whether the officer would face charges or not, the city was bracing for protests.
Shops had put up plywood coverings and the courthouse had been surrounded with concrete barriers and metal fencing.
Kenosha's mayor has been given emergency powers to impose curfews, and 500 national guard troops had been sent by Governor Tony Evers to the area.
Mr Sheskey was one of a number of officers who, on 23 August, responded to a call from a woman that her boyfriend was not supposed to be around.
The Kenosha police union said that Mr Blake had a knife that he was ordered to drop several times by Mr Sheskey.