Washington (CNN) -- Two hours after first being notified of an attack on the U.S. diplomatic mission in Benghazi, Libya, a government e-mail to the White House, the State Department and the FBI said an Islamist group had claimed credit, according to a copy obtained by CNN. An initial e-mail was sent while the attack was still underway, and another that arrived two hours later -- sent from a State Department address to various government agencies including the executive office of the president -- identified Ansar al-Sharia as claiming responsibility for the attack on its Facebook page and on Twitter.
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NEW: Secretary of State Hillary Clinton says don't "cherry pick" documents
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The White House says it received conflicting information about the attack
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A government email on the day of the attack says an Islamist group claimed credit
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The attack left U.S. Ambassador Christopher Stevens and three other Americans dead
Two @placeholder officials, speaking on condition of not being identified on Wednesday, said the government e-mails about the attack were not an intelligence assessment.