Residents of Charlotte, North Carolina, woke to a state of emergency on Thursday with National Guard troops deployed on the streets after a second night of violent protests over the fatal police shooting of a black man.

One person was on life support after being shot by a civilian late Wednesday as riot police used tear gas, rubber bullets and flash-bang grenades to try to disperse demonstrators who looted stores and threw rocks, bottles and fireworks.

Four police officers suffered non-life threatening injuries, city officials said.

The latest trouble erupted after a peaceful rally earlier in the evening by protesters who reject the official account of how Keith Scott, 43, was gunned down by a black police officer in the parking lot of an apartment complex on Tuesday afternoon.

Authorities say Scott was wielding a handgun and was shot after refusing commands to drop it. His family and a witness say he was holding a book, not a firearm, when he was killed.

A spokesman for the Charlotte Fraternal Order of Police told CNN on Thursday he had seen video from the scene showing Scott holding a gun.

Scott's wife, Rakeyia Scott, said on Wednesday evening that her family was "devastated" and had "more questions than answers" about her husband's death.

She said she respected the rights of those who wanted to demonstrate, and asked that they do so peacefully.