The shooter claimed he was working for ISIS.
Local 10 has the video. The shooter is reported to be "in custody."
Update: CBS reports:
According to the Associated Press, the Pentagon said he went AWOL several times as a specialist during a stint with the Alaska National Guard and was demoted to private first class. He was given a general discharge, which is different from an honorable discharge.
In November 2016, he walked into an FBI office in Anchorage claiming that he was being forced to fight for ISIS and was sent to a psychiatric hospital, officials revealed.
In 2011 or 2012, he was investigated by Homeland Security Investigations for child porn. Three weapons and a computer were seized, but there was not enough evidence to prosecute, according to law enforcement sources.