DALLAS (CBSDFW.COM) – Social media posts by the man who officials say opened fire at the Earle Cabell Federal Building in downtown Dallas give insight into the alleged shooter’s state of mind.

Brian Isaack Clyde, 22, posted extensively about guns and ammunition on Facebook.

“We are aggressively pursuing all his social media activity,” FBI Special Agent in Charge, Matt DeSarno told reporters Monday afternoon.

WARNING GRAPHIC VIDEO BELOW

Clyde was taken to Baylor hospital and pronounced deceased on scene after Monday morning’s attack.

At a morning press conference FBI Dallas Special Agent in Charge Matthew DeSarno explained, “Shortly after the incident began this morning officers from the Federal Protective Service engaged the shooter who was later identified as Brian Isaack Clyde.”

The FBI is working to figure out where Clyde got the gun he used in the attack.

From his Facebook cover photo showing Civil War uniforms, to rants about the U.S. government — including talking about Ruby Ridge and the Branch Davidians… Clyde shared his views openly.

In 2018, Clyde shared a picture showing him with a gun, writing, “When the yeyo deal goes south.” He also posted a photo showing ammo.

He also shared a drawing of a person crying and the words: “In this state, I am in a realm of Euphoria. Not because of a false God, but because I am enlightened.”

Clyde posted a video on June 9, in which he said, “I don’t know how much longer I have… the storm is coming…let’s do it” and held up a gun. The caption reads, “This storm is about to pay for kicking me off my porch.”

In April, Clyde shared an image of a plaque from Del Mar College in Corpus Christi, which read “outstanding student award. Brian Isaack Clyde. Non-destructive applied technology. 2019.” In 2017, he wrote, “Welp, I’m a certified armed security guard more commonly known as a rent-a-cop. I can also be a bounty hunter.”

A Facebook post from 2017 shows Clyde in a military uniform.

Dallas ISD confirmed Clyde attended Woodrow Wilson as a freshman. He withdrew March 1st, 2012.

Private 1st Class Clyde served as an infantryman in the Army from August 2015 to February 2017.

Authorities are asking anyone with information about the shooting to call 1.800.Call.FBI