A police officer in North Carolina has been charged with voluntary manslaughter after fatally shooting an unarmed man who had apparently been in a wreck and was seeking help, authorities said. The victim, Jonathan Ferrell, 24, played football for Florida A&M University in 2009-10, school officials said Sunday.

An attorney for the victim's family said on Sunday he believed race played a role in the death of Ferrell, who was black.

"If Mr Farrell 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.

Ferrell was seeking help at a house early on Saturday, after driving a vehicle that crashed into trees in northeast Charlotte, according to Charlotte-Mecklenburg police. A woman answered the door and, when she didn't recognise the man, called the police emergency dispatcher.

Officers responding to the breaking-and-entering call found Ferrell a short distance from the home, police said. As they approached him, Ferrell ran toward the officers and was hit with a Taser. Police said he continued to run toward them when officer Randall Kerrick fired his gun, hitting Ferrell several times. Ferrell died at the scene.

Police called Ferrell and Kerrick's initial encounter "appropriate and lawful". But in a statement late Saturday, they said "the investigation showed that the subsequent shooting of Mr Ferrell was excessive" and "Kerrick did not have a lawful right to discharge his weapon during this encounter".

Police said Kerrick had been charged with voluntary manslaughter, which under North Carolina law involves killing without malice using "excessive force" in exercising "imperfect self-defense".

Police are not expected to further describe the incident on Sunday, CMPD spokesman Officer Keith Trietley said.

Kerrick, 27, turned himself in for booking on Saturday evening and was released on a $50,000 bond, according to the Mecklenburg County Sheriff's Office website. Kerrick joined the police force in April 2011.

FAMU interim athletic director Michael Smith confirmed on Sunday that Ferrell played the safety position for the school's football team during the 2009 and 2010 seasons. "Our hearts and prayers go out to his family during their time of bereavement," Smith said in an emailed statement.

A public records search indicated that Ferrell began living in Charlotte early this year after moving from Tallahassee, Florida, home to FAMU.

Before Kerrick was charged, police chief Rodney Monroe describe the accident in a news conference. He said the wreck was so severe Ferrell would have had to climb out of the back window to escape. Monroe said he didn't know what caused the crash and didn't say whether Ferrell suffered injuries, The Charlotte Observer reported.

Ferrell apparently walked about a half-mile to the nearest house and was "banging on the door viciously" to attract attention, Monroe said. Thinking it was her husband coming home late from work, the woman who lives there opened the door. When she saw Ferrell, she shut it and called police about 2.30am, Monroe said. Monroe said he didn't think the unarmed Ferrell made threats or tried to rob the woman.