A longtime Walmart employee who leapt into action and ushered dozens of people to safety when a gunman opened fire at his El Paso, Texas, store may have saved more than 100 lives thanks to his selfless heroism.

Gilbert Serna, who has worked at the same Walmart for almost 19 years, said he was standing near the back of the store on Saturday when he heard a panicked voice announce a “code brown” over his two-way radio — a warning that a shooting of some kind had occurred.

Within moments, Serna told BuzzFeed that he heard the “pop, pop, pop” of gunfire. He immediately launched into action, he said ― signaling to customers and colleagues to follow him out of the store through a fire exit at the back.

Once outside, Serna said he opened four shipping containers and told the group to hide there. The father of two estimated that he’d led around 100 people out of the besieged Walmart.

“They were scared. I was scared. We were all scared,” he told BuzzFeed.

Serna could’ve hidden with the group but instead, he closed the containers’ doors and headed towards the parking lot where dozens of people, including a girls’ soccer team that had been outside fundraising, were standing in the open, CNN reported.

Serna reportedly helped to lead this second group ― of about 50 to 60 people ― to a neighboring Sam’s Club, where he told them to wait for police. 

As he was assisting others to safety, Serna said it became clear that he was living through a major act of violence. 

“I noticed people with gunshot wounds to their legs, arms, thighs, some graze wounds. That’s when it really hit me — like, oh man, this guy’s out to kill people,” he told BuzzFeed, adding that he saw someone carrying a baby covered in blood. 

“I can’t get that image out of my head,” he said.

As CNN noted, Serna was among the many heroes who risked their lives on Saturday to help others in need.  

Several Walmart employees were outside the store helping people escape the violence and picking people up with their cars, the station said. 

Adria Gonzalez, a teacher who had been in the Walmart shopping with her mom, stopped to help people escape the store when the shooting began. 

Glendon Oakley, an off-duty Army serviceman, has been credited with rescuing several children during the attack.

Oakley had been shopping at a nearby Foot Locker when he said he heard gunshots. Seeing multiple children alone and crying in the ensuing chaos, Oakley grabbed as many kids as he could and carried them to safety.