Brian Williams has voluntarily stepped down from NBC Nightly News for several days while his network investigates his false claim that his helicopter came under fire during the Iraq war in 2003.

"In the midst of a career spent covering and consuming news, it has become painfully apparent to me that I am presently too much a part of the news, due to my actions," Williams said in a staff memo obtained by TVGuide.com.

"As Managing Editor of NBC Nightly News, I have decided to take myself off of my daily broadcast for the next several days, and Lester Holt has kindly agreed to sit in for me to allow us to adequately deal with this issue," he continued. "Upon my return, I will continue my career-long effort to be worthy of the trust of those who place their trust in us."

On Friday, NBC News launched an internal investigation into the circumstances surrounding Williams claim, which he has since recanted and apologized for on air.

Brian Williams' alleged pilot withdraws account

"This has been a difficult few days for all of us at NBC News," NBC News president Deborah Turness said in a staff memo on Friday.

For now, Turness appears to be standing by Williams, who has been the NBC Nightly News anchor for more than a decade. In the memo, she explained to staffers that Williams "specifically expressed how sorry he is for the impact this has had on all of you and on this proud organization."

"As you would expect, we have a team dedicated to gathering the facts to help us make sense of all that has transpired," Turness continued. "We're working on what the best next steps are - and when we have something to communicate we will of course share it with you."

According to the New York Daily News, which was first to report the investigation, the head of NBC's investigative unit Richard Esposito is in charge of the investigation.

Last week during his broadcast, Williams intended to honor a veteran whom he claimed rescued him when a helicopter carrying him was forced down by enemy fire in Iraq. After commenters began accusing Williams of lying about riding in the helicopter that was shot down, he apologized on-air Wednesday night.

Williams never admitted to purposefully lying and instead cited a faulty memory. Since then, three men have come forward contradicting Williams' story. However, a fourth man, Richard Krell, initially claimed to have piloted the anchor's helicopter that day and said they did come under "small arms fire." But Krell is now recanting his initial statements and saying he also might have remembered the incident wrong.

The scrutiny on Williams prompted by this incident has inspired many to question stories stemming from his coverage of Hurricane Katrina in 2005. Specifically, there are doubts surrounding Williams' claim that he saw a body floating in the French Quarter, which barely suffered from any flooding.