An unarmed man has been shot dead by police in the United States as he was running towards officers following a car crash.

A police officer in Charlotte, North Carolina, has been charged with voluntary manslaughter for the shooting of 24-year-old Jonathan Ferrell.

An attorney for Mr Ferrell's family says he believes race played a role, as the victim was black.

"If Mr Ferrell was not black or brown, wouldn't they have asked him a few questions before showering him with bullets?" said attorney Chris Chestnut, who said he would request all police evidence from the shooting.

Mr Ferrell, seeking help after crawling out of his wrecked car in a nearby forest, knocked on a door in a predominantly white neighbourhood, Mr Chestnut said.

The Charlotte-Mecklenburg Police Department said a woman called 911 after Mr Ferrell began knocking insistently on her door at about 2:30am.

Police said the woman immediately closed the door on Mr Ferrell after seeing it was not her husband.

Three police officers arrived, finding Mr Ferrell a short distance from the woman's house.

As soon as the officers got out of their vehicles, he started running toward them, police said.

One officer unsuccessfully fired a Taser at Mr Ferrell, and he kept running.

Randall Kerrick, another officer, then shot Mr Ferrell several times with his service weapon, killing him.

Police later found Mr Ferrell's wrecked car.

Mr Kerrick has been charged with voluntary manslaughter, while all three officers have been placed on administrative leave.

"Our investigation has shown that Officer Kerrick did not have a lawful right to discharge his weapon during this encounter," the police department said in a statement.

Mr Ferrell was a former football player for Florida A&M University in Tallahassee.

He recently moved to Charlotte with his fiancee to continue his studies at Johnson C Smith University, Mr Chestnut said.

He was on the Florida A&M roster in the 2009 and 2010 seasons, the university said in a statement.

Reuters