DALLAS (AP) - The FBI says a 22-year-old man who opened fire on a federal courthouse in Dallas was honorably discharged from the U.S. Army.

The Army says Brian Isaack Clyde served as an infantryman from August 2015 to February 2017 and achieved the rank of private first class. He never deployed to a war zone.

Clyde's period of service was shorter than a typical Army contract, suggesting he left the military earlier than planned.

Clyde was shot and killed by courthouse security Monday after opening fire on the Earle Cabell Federal Building with a high-powered rifle. He approached the downtown courthouse dressed in a black mask and heavy vest, carrying more than 150 rounds of ammunition.

Investigators haven't determined a motive. The courthouse reopened for regular business Wednesday.

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