A "little kid" tried to warn shoppers that a gunman was shooting people. No one listened.

On Saturday afternoon local time, a gunman killed 20 people in a crowded Texas Walmart where many shoppers were purchasing back-to-school supplies.

The suspect has been identified as 21-year-old Dallas native Patrick Crusius, who was arrested at the El Paso shopping mall after his attack.

Glen Oakley, who has been hailed a hero for trying to save kids during the rampage, has recalled a child who tried to warn shoppers of an active shooter, but who was largely ignored.

“I was buying a jersey and a little kid ran in there and started telling us there was an active shooter in Walmart,” Oakley, a man who happens to be in the military, told an American journalist.

“We didn’t pay him no attention because for one, he was just a little kid and for two, we were at the mall, the Walmart so we didn’t pay him no mind.”

Oakley explained he then walked to Footlocker, where he heard the first gunshots.

“I don’t know how the kid knew about the shooter but he was running around trying to tell people and they were paying no attention,” Specialist Oakley recalled.

This is Glen Oakley.

He was in the @FootLocker when the El Paso shooting happened. When he ran to leave, he saw kids in the mall without their parents, scared and alone.

So he picked up as many as he could and carried them to safety.

Focus on the heroes.#ElPasoShooting pic.twitter.com/1NofPvegjL

— Muhammad Lila (@MuhammadLila) August 3, 2019

The witness of the shooting shared he was determined to save the children he saw that were without their parents.

“I saw a whole bunch of kids just running around without their parents,” he said. “I was trying to pick them up, one by one, as many as I can and just run out … it was just a whole bunch of kids in there. I’m sorry, I’m shaking.

“I was just so worried about those kids, man,” Oakley continued. “I was just trying to pick up those kids, man. I wasn’t really worried about myself … I just hope those kids are all right. That’s all I’m thinking about is the kids.”

What happened at the El Paso shooting?

A gunman opened fire inside a Walmart store in El Paso, Texas. Texas Governor Greg Abbott says 20 people were killed.

Many of those in the store were buying back-to-school supplies when they were caught up in the rampage, which came just six days after a teenage gunman killed three people at a food festival in Northern California.

Video has emerged of the panicked shoppers being evacuated from the mall by police after the shooting.

“Hands up! Hands up! Hands up! Let’s go!” officers are heard yelling at shoppers.

El Paso police Sergeant Robert Gomez said the suspect was taken into custody without incident.

US President Donald Trump has labelled the mass shooting an “act of cowardice,” and said there “are no reasons or excuses that will ever justify killing people.”

On top of those who have tragically lost their lives, it is believed there are more than 26 people who have been injured and taken to hospital.

For more, read:

“Shoppers fled for their lives.” 20 people have been killed by a gunman at back-to-school sale.