Brian Williams Taking Himself Off Air Temporarily

NBC anchorman Brian Williams says he's temporarily stepping away from his nightly newscast amid questions about his credibility.

In a message sent to NBC News staff and released by NBC on Saturday, Williams says it has "become painfully apparent" to him that his actions have made him too much a part of the news.

Williams recently apologized for falsely saying on the air that he was in a helicopter hit by a rocket-propelled grenade while in Iraq in 2003.

NBC News President Deborah Turness said in an internal memo Friday that the network has assigned the head of its own investigative unit to look into Williams' statements.