Police fired tear gas on Monday when a protest demanding racial justice in the city of Kenosha in the state of Wisconsin turned violent, as rage builds once more in the US at the shooting of a black man by a white officer.

Clashes erupted for a second night after a video circulated showing 29-year-old Jacob Blake being shot and wounded in the back multiple times by police on Sunday with his three children watching.

Shortly after a curfew imposed on Kenosha County began at 8:00pm (0100 GMT on Tuesday), local police dressed in crowd control gear began pushing protesters back from outside a county courthouse using tear gas.

They fired after the demonstrators began throwing water bottles at the Kenosha County Sheriff’s officers. Some protesters then launched fireworks and more bottles at officers.

The clashes came hours after some two dozen police faced off against hundreds of demonstrators chanting “No justice, no peace” and “Say his name – Jacob Blake”.

Blake, 29, was airlifted to the hospital in Milwaukee in serious condition, but local media reported on Monday afternoon that his family said he was out of surgery and improving.

Kenosha County, on the shores of Lake Michigan, has declared a curfew from 8:00pm until 7:00am on Tuesday, after protesters set alight several city vehicles and damaged the county courthouse late on Sunday.

County sheriff David Beth said in a statement: “The public needs to be off the streets for their safety.”

Wisconsin governor Tony Evers said he was sending 125 members of the National Guard to the city to maintain order on Monday night.

He urged protesters to be peaceful, adding: “We must see the trauma, fear and exhaustion of being black in our state and our country.”

One couple, who only gave their names as Michelle and Kalvin, had brought their seven-year-old daughter and eight-year-old son with them.

Michelle said: “I want my kids to see how change happens and am here so nothing like this ever happens to them.”

Another resident, 37-year-old Sherese Lott, called for police to be held accountable in such killings.

She said: “If I killed someone I’d be convicted and regarded as a murderer. I think it should be the same for the police.”