Chattanooga, Tennessee (CNN) In the hours after he fatally shot four U.S. Marines and a Navy sailor, close friends of Muhammad Youssef Abdelazeez discussed whether his motivation was jihad, or something else.

Text messages obtained exclusively by CNN reveal shock and disbelief when Abdelazeez's close friends learned the name of the gunman who opened fire on two military centers in Chattanooga.

"It can't be our abdulaziz (sic) .." wrote James Petty, a close friend who considered the 24-year-old a devout Muslim and his spiritual mentor.

The text messages were sent in a group thread on WhatsApp. Petty said this was a close group of friends who communicated regularly about Islam among themselves and with Abdelazeez. Petty gave the texts to CNN on condition that the names of the other people in the conversation not be published.

One friend wrote, "#chattanooga on twitter it can't not be him."

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