At least nine people were injured and 44 arrested during the second night of violent protests in Charlotte, North Carolina, after police shot dead a black man, said the city's police chief.

One man remains in critical condition after being shot on Wednesday, said Kerr Putney, the chief of the Charlotte-Mecklenburg police. Police used tear gas, rubber bullets and stun grenades to disperse protesters who looted shops and hurled rocks and fireworks at officers, he said.

It comes as a state of emergency was declared in the city and the National Guard deployed in response to the unrest.

In the press conference Putney said officers were investigating claims the man injured on Wednesday was shot by police, after officials initially claimed he was shot by a civilian.

"We're here to seek the truth, so we're investigating that to find the truth, the absolute truth as best as the evidence can show us," Putney said, as quoted by Reuters.

Among the injured were four police officers, city officials said, who did not suffer serious injuries.

The trouble came after a peaceful protest against the killing of Keith Scott, 43, who was gunned down in the car park of a block of flats by a black officer on Tuesday.

Putney said that police would not be releasing a dashcam video of Scott's shooting "to the masses", reported CNN. It would be inappropriate to release footage of "a victim's worst day" for public consumption, Putney said. Scott's family has asked to see the footage, and he hoped to accommodate their request, he said.

Sixteen police officers and several protesters were injured after protests became violent on Tuesday. Police claim that Scott was holding a handgun and refused commands to drop it before being shot. Scott's friends and family claim he was holding a book.

Putney said that the footage did not provide "definitive" evidence Scott pointed a gun at police oficers, but eyewitness statements supported the police account.

It is the latest in a series of killings of black men by police in the US, who critics accuse of racial bias and excessive use of force.

Charlotte protests
Charlotte protests: a demonstrator confronts a police officer following the killing of a black man by a police officerGettyImages