"I did what any good man would have done," he told CNN's Chris Cuomo, who on Mondayvisited Del Sol Medical Center, where Grant was recovering from gunshot wounds he might well have avoided had he not tried to stop the shooter who killed 22 people and left another 24 injured two days earlier at a shopping center in El Paso, Texas.

"I heard gunshots, and knew what it was, so I ran towards my mother to try to shield her," Grant explained.

Though his mom is "a gun-wielding grandma," she made the unusual decision Saturday morning to leave her Smith & Wesson .38 Special at home, since they were "just going to Walmart," Grant said. "So, when I went to her, no gun."

Meanwhile, from his position just inside the store's front door, Grant could see the shooter outside in the parking lot "popping people off" with an assault rifle. As his mother hustled to safety at the back of the store, Grant decided he would try to deter the shooter.

"I started throwing random bottles at him," said Grant. "I'm not a baseball player, so one went this way, one went that way." One bottle, though, found its target.

Grant ducked as the gunman, who had spotted and homed in on him, started firing off rounds.

"When I got hit, it was like somebody put a hand grenade in my back and pulled the pin," Grant said. Struck, bleeding, he lay on the floor and watched the shooter walking among those who were praying in Spanish, begging for their lives.

"They were on the ground, and he still shot them in the head ... He had no remorse for their lives at all ," said Grant, who noted the khaki pants and shooting glasses worn by the gunman: "I could just tell he was prepared."

Though naturally talkative, Grant paused as tears threatened to overwhelm him. "One little girl saw her parents get killed right in front of her," he said. "How much hate do you have to have in your heart to do that?"

A desire to "do something" to end the horror forced Grant to his feet. Running through the store, he reached the auto department, where he burst through a set of doors "and there was my guardian angel," he said, referring to US Customs and Border Protection Agent Donna Sifford.

"There's a shooter inside! Code Brown!" he yelled to Sifford and others, having learned the military code from his father.

Sifford, an off-duty CBP agent, was in the same, unusual position as Grant's gun-toting mother. She, too, had left her firearm at home before making the trek to Walmart that morning.

Still, as a trained law enforcement officer, she felt an obligation to do all that was possible under the circumstances, she explained to Cuomo at the hospital as she reunited with Grant.

"We were trying to get as many people as possible out," she said.

Working with two Walmart employees "who were absolutely phenomenal," Sifford had already rescued one confused older woman. When Grant arrived, the Walmart helpers grabbed first aid kits and paper towels and helped Sifford take him out of the store.

"We didn't know where the shooter was. We ducked down between two vehicles on the northeast side of Walmart," said Sifford, who was trying to keep Grant calm. "Chris was fading, losing a lot of blood."

His wounds were life-threatening. She knew she needed to stay put to help Grant survive.

An off-duty cop with a pickup truck eventually came to their rescue. Sifford helped Grant into the bed of the truck, and the driver rushed him to the hospital.

Sifford and Grant embrace two days after the mass shooting.

Reunited with Grant a day later, Sifford said: "We bonded out there, and I'm just happy to see he's doing well."

The newfound "forever friends" shared a common perception of the shooter, described by Sifford as "a hateful coward -- to come in and shoot children and innocent people."

Grant remains troubled by the notion that he did not deserve to escape with his life while children died, he said.

"If I could trade my life for that little girl's life I saw killed, I would do it in a second," Grant said. "She had school supplies. I'm 50 years old. My life is almost over, so I would have traded my life for that life any day of the week. Why would you kill an innocent child?"