The governor of the southern US state of North Carolina has declared a state of emergency following a second night of unrest in Charlotte ignited by the fatal police shooting of a black man.

According to police 43-year-old Keith Scott was shot and killed by officers on Tuesday after he refused to drop a handgun.

His family and a witness to the shooting said Mr Scott was holding a book, not a firearm.

Governor Pat McCrory said the National Guard and state Highway Patrol troopers would be sent in to help police in Charlotte restore and maintain order.

One protester was shot and critically injured, and four police officers suffered non-life threatening injuries, city officials said on Twitter.

Authorities said that the shooting was "civilian on civilian," and that police did not open fire.

Charlotte Police Chief Kerr Putney said nine people were injured during the protests and 44 had been arrested.

Mr Scott's wife, Rakeyia Scott, issued a statement describing her family as "devastated" and appealing for calm.

"We have more questions than answers about Keith's death," the statement said.

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Last night protesters smashed windows and glass doors at a nearby Hyatt hotel, whose manager told Reuters that two employees were punched. The slogan "Black Lives Matter" was spray-painted on windows.
           
Demonstrators were also seen looting a shop after smashing its windows and a shop that sells athletic wear for fans of Charlotte's National Basketball League team, the Hornets. Others set fire to rubbish bins.

It was the second night of unrest in North Carolina's largest city and one of the biggest US financial centres.

Several protesters and 16 officers were injured on Tuesday night.

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The unrest prompted Governor McCrory to declare a state of emergency to help restore peace.

"Any violence directed toward our citizens or police officers or destruction of property should not be tolerated," Mr McCrory said in a statement.

The American Civil Liberties Union urged police to release their camera footage of the incident in which Mr Scott was shot.

Police vehicles typically have a dashboard camera and officers are required to carry cameras on their persons.

Authorities have not released any video of the incident but the city's mayor said she would view the footage today.

Jennifer Roberts was also considering a curfew as Bank of America told employees not to report to work at its offices, local media reported.

Governor McCrory said he was acting at the request of the Charlotte police chief in sending National Guard and state troopers to assist local law enforcement.

There have also been protests in Tulsa, Oklahoma, in recent days after a police officer was seen in a video last week fatally shooting an unarmed black man who had his hands in clear view at the time.

The officer - Betty Shelby - has since been charged with manslaughter.