Under growing public pressure to explain the incident, NBC News President Steve Capus provided Reuters with the fullest explanation to date of how the edited call made it on air and what the network is doing to prevent such a consequential error from happening again.

Capus confirmed a previous Reuters report that an internal network investigation had determined that a producer made the editing error, and that the network's editorial controls - including senior broadcast producer oversight, script editors and often legal and standards department reviews of sensitive material to be broadcast - simply missed the selective editing of the phone call.

He said the producer has been fired and "several people" involved were disciplined, though he declined to specify the nature of the disciplinary actions, saying they were internal personnel matters.

Sources at the network told Reuters on Thursday that NBC News executives did not know the emergency call was misleadingly edited until news reports surfaced days later on blogs including newsbusters.org and Breitbart.com.

Those blogs, along with media critics and rival networks, have charged that the edited call has inflamed racial tensions in an already volatile situation.

Sources inside the network have told Reuters that NBC News brass interviewed more than a dozen staffers during its investigation of the matter.

As part of the investigation, the producer who edited the call was questioned extensively about motivation, and it was determined that the person had cut the video clip down to meet a maximum time requirement for the length of the segment - a common pressure in morning television - and inadvertently edited the call in a way that proved misleading.

NBC News has apologized for the incident