An Iraq War veteran was killed in Friday's shootings at a Planned Parenthood clinic in Colorado Springs, Colo., while trying to save others, family members said.

Ke'Arre Stewart, a 29-year-old who served in the U.S. Army's Fourth Infantry Division, had stepped outside the clinic to get cellphone service when he was shot, his brother, Leyonte Chandler, told NBC News.

Stewart then ran back inside to try to help others.

"He tried to run back inside the building — well, he did — and tell the other people inside, you know, 'Take cover, get down.' People started taking cover, hiding in bathrooms and whatnot," Chandler said. "I believe that's his military instinct, you know: Leave no soldier behind, leave no civilian behind, just leave no one behind. I don't know where he was at, as far as how many more breaths he had, but he knew. And before his time ran out, I guess that was his main priority: to help and save other lives."

"He was just a standup guy; he would take a bullet for you," Amburh Butler, a lifelong friend, told The Associated Press. "He was the most sincere person I'd ever met."

Chandler added: "People were terrified, people were crying and scared, seeing other people get shot ... I believe my brother put his life on the line to prevent that. That's definitely heroic."

Stewart, a father of two young girls, was stationed at Fort Carson in Colorado Springs until 2014, when he was discharged.

Chandler called his brother "a tremendous father, a wonderful father."

Stewart was one of three people killed after the alleged gunman, 57-year-old Robert Lewis Dear, opened fire at the clinic.

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Garrett Swasey, a police officer at the University of Colorado's Colorado Springs campus, was killed while responding to the call to assist with an active shooter at the nearby clinic.

Swasey, a 44-year-old married father of two, was a co-pastor at a local evangelical church and a former competitive figure skater who won a national championship as a junior.

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"He was literally like a little brother to me," figure skater and Olympic medalist Nancy Kerrigan said Sunday. "I saw him every day. We trained together."

Jennifer Markovsky, a 36-year-old mother of two, was killed while accompanying a friend to the clinic, her father, John Ah-King, told the Denver Post.

"I miss you, my daughter," he wrote on Facebook. "Life was too short."

Five other officers and four other civilians were wounded in the attack.

Dear is expected to appear in court Monday.