17-year-old arrested after two shot dead in protest-hit US city of Kenosha

A 17-year-old was arrested on murder charges Wednesday after two people were shot dead and a third wounded during anti-police protests in the US city of Kenosha, as President Donald Trump said he was sending in additional federal forces.

Outrage continued to spread after Kenosha police shot African American Jacob Blake in his back point-blank multiple times in the Midwestern city last Sunday, as city officials urged patience while an state investigation is underway.

The NBA cancelled all three playoff games Wednesday after the Milwaukee Bucks, whose home base is just to the north of Kenosha, boycotted their game in protest of Blake's shooting.

"We're tired of the killings and the injustice," Bucks player George Hill was quoted by The Undefeated website as saying.

The boycott also spread to baseball, with the Milwaukee Brewers refusing to play their Major League Baseball game against the Cincinnati Reds Wednesday, according to US media.

Kenosha city officials ordered a 7 pm to 7 am curfew through Sunday in hopes of bringing calm after Tuesday's violence, which occurred as armed vigilantes flocked to the site of protests saying they were there to defend private property.

Videos taken overnight Tuesday show one of the vigilantes shooting at protesters with an assault rifle and apparently hitting two who tried to stop him.

The man then walks down the street freely, gun slung across his chest, while protesters scatter and police vehicles drive past him.

Two men were killed and one wounded in the arm in the shooting.

Police in Antioch, Illinois, about 20 miles (32 kilometres) southwest of Kenosha announced Thursday afternoon that they had arrested a 17-year-old wanted in Kenosha for murder.

The suspect is widely identified as Kyle Rittenhouse.

Antioch court records indicate that Rittenhouse had been arrested as a fugitive on Thursday and would face a hearing on his extradition to Wisconsin on Saturday.

"This morning Kenosha County authorities issued an arrest warrant for the individual responsible for the incident, charging him with First Degree Intentional Homicide," Antioch police said in a statement.

Blake, whose shooting sparked the unrest, remained hospitalized Wednesday and may be permanently paralyzed from the waist down, according to his family.

His mother Julia Jackson pleaded for an end to the violence.

"For anyone who is doing anything that is violent or destructive, please stop," she said in an interview Wednesday with ABC News.

"I get your pain. I get your frustration. This is nothing new and it's not just about my son, I get that. But please find another way."

Trump announced he was deploying federal law enforcement and national guard troops to Kenosha "to restore law and order."

"We will NOT stand for looting, arson, violence, and lawlessness on American streets," Trump tweeted.

But local officials said they already had hundreds of police from around the state, some 250 national guard troops, and FBI and federal marshals helping them with the situation.

"I know people are looking for justice," said Kenosha County Sheriff David Beth in a press briefing.

But he stressed that people had to obey the curfew.

"We've got more resources coming in," he said. "We're not going to put up with what we saw Monday night," when cars and buildings were burned by protestors.

Kenosha city Police Chief Daniel Miskins appeared before the media for the first time since Sunday but refused to answer questions on Blake's shooting.

The details of the incident remain unexplained, while the police officers involved have been suspended.

Bystander video shows one officer shooting Blake multiple times in his back as he tried to enter his car, which held his three sons, after what various witnesses describe as his intervention in a domestic incident.

Blake's father Jacob Blake Sr. accused police of "senseless attempted murder".

Miskins acknowledged anger over the lack of information on the incident, but said it was now in the hands of state investigators and he could not talk about it.

The most recent police shooting of an African American has sparked renewed outrage and protests in US cities and further fuelled the Black Lives Matter movement.

It is expected to become one focus of a planned march on Washington this weekend by African Americans led by activist Al Sharpton.

But Trump's comments made clear it would also be fodder for the ongoing presidential race with the election just over two months away.

Trump's campaign has portrayed anti-police protests in numerous cities as an extreme leftist threat to the country.

Democratic rival Joe Biden called for an end to violence after Blake's shooting.

"Once again, a Black man - Jacob Blake - was shot by the police. In front of his children. It makes me sick," Biden tweeted Wednesday.

"Is this the country we want to be? Needless violence won't heal us. We need to end the violence-- and peacefully come together to demand justice," he wrote.