A white US police officer has shot and killed a 13-year-old black boy in the state of Ohio while chasing down suspects of a reported robbery, after the teenager allegedly pulled out a pellet gun.

Police in the town of Columbus, where the incident took place, said they were investigating Wednesday's killing of Tyre King, the latest in a string of shootings of African Americans by law enforcement officers that have fuelled protests and national debate about policing tactics in US cities.

"We got a call on 911 saying that an armed robbery was being reported," police chief Kim Jacobs said at a news conference on Thursday.

"Once they [officers] arrived at that scene they saw some people that they believed matched the description of the suspects and tried to track down those suspects.

"A confrontation happened and there was a policeman involved in shooting," said Jacobs, adding that "one of the officers fired and as result of that the young man succumbed to his injuries".

Police said King was shot multiple times after he pulled out a BB gun – a low-powered air gun which shoots small round pellets – during the confrontation, and was later pronounced dead at Nationwide Children's Hospital.

Police promised to investigate the case "thoroughly", but lawyers for King's family called for an independent investigation, saying some witness accounts conflicted with the police version of what happened, according to the Associated Press news agency. 

The lawyers said allegations about King cannot be considered fact until there's a "thorough,unbiased investigation".