This once young poolee who rushed a school shooter when his classroom was attacked has become a Marine.

Brendan Bialy was a high school senior in May when a gunman entered his classroom at STEM School Highlands Ranch in Colorado.

Instead of running at the sound of gunfire, he and his friends tried to tackle the shooter.

“Brendan’s courage and commitment to swiftly ending this tragic incident at the risk of his own safety is admirable and inspiring,” the 8th District Marines said at the time of the shooting.

That same commitment led Bialy, from Castle Rock, Colorado, to Marine Corps boot camp. He became a Marine on Sept. 20 in San Diego, according to the Marine Corps, even earning the accolade of graduating as platoon honor man and a meritorious promotion to private first class.

Pfc. Brendan M. Bialy, the 18-year-old guide of Platoon 2147, Golf Company, 2nd Recruit Training Battalion, is from Castle Rock, Colorado. (Lance Cpl. Grace J. Kindred/Marine Corps)
Pfc. Brendan M. Bialy, the 18-year-old guide of Platoon 2147, Golf Company, 2nd Recruit Training Battalion, is from Castle Rock, Colorado. (Lance Cpl. Grace J. Kindred/Marine Corps)

“I don’t necessarily think recruit training changed Bialy ― I think he is who he was when he first got here,” drill instructor Staff Sgt. Marcus Chestnut said in a Marine Corps video. “I think we just gave him some additional attributes that made him a stronger man.”

Bialy had joined the Marine Corps Delayed Entry Program on July 12, 2018, out of Recruiting Substation Parker, Colorado, according to a May Marine Corps press release.

His Highlands Ranch, Colorado, STEM School is a 15 minute drive from Columbine High School in Littleton, Colorado, the site of the 1999 school massacre where 12 students and a teacher were killed by school shooters.

Bialy’s friend Kendrick Castillo, 18, was killed in the May Colorado shooting. Eight others were wounded.

Both alleged shooters ― an 18-year-old and a 16-year-old ― were arrested and are awaiting hearings, according to The Associated Press.

Bialy is now headed the School of Infantry, then onto training to be an electro-optical ordnance repairer, Stars and Stripes first reported.

“My thoughts on becoming a Marine were nothing but reinforced after the shooting,” Bialy said in a Marine Corps video.

“What I saw that day was complete and total malevolence and bad overcome by good.”

Andrea Scott is editor of Marine Corps Times. On Twitter: @_andreascott.