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It was a scene out of a watery hell: A vehicle flipped over by a flooded Texas highway, good Samaritans trying desperately to pull two trapped babies out, a blaring horn, the crackle of thunder, the desperate cries of rescuers racing against time.

Jaime Martinez, who was heading to a party with a pal on Saturday when he came across the rescue-in-progress, knew just what to do. Thirty years ago, he had been a firefighter in Guatemala, and he never dreamed he would need to tap that training again.

"It was something that I can't believe happened," Martinez, 58 and overcome with emotion, told NBC News on Monday. "People were crying, there was a lot of confusion. The parents were still in the car at the time. Everyone was trying to do as much as they could do."

The lengths Martinez and the others went to save the children from drowning on a road near Canton, Texas, were captured on a video obtained by NBC News.

"Give me the baby! Give me the baby!" Martinez is heard yelling. "Give me the baby here! Give me the baby!"

Martinez immediately begins performing cardiopulmonary resuscitation while another man can be heard yelling, "C'mon baby! C'mon!"

"In the name of Jesus, give him breath, Lord, give him breath, Lord, in the name of Jesus," a woman cries out as Martinez tries to breathe life back into the unconscious child.

"Don't stop," another desperate man cries out. "Lord! Lord! Please Lord!"

"Breathe in the Lord," a woman prays while Martinez keeps working on the child. "In the name of Jesus, breathe in the Lord."

Then, suddenly, good news.

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"She is breathing," a man says. "C'mon baby, you can do it," a woman says.

Thanks to Martinez and the other heroes who stepped up to help, 18-month-old Addy Ocheltree and her brother, Marshall, 4 months, survived. Marshall was released from the Children's Medical Center of Dallas. Addy was stable in a hospital, her parents told NBC News.

Phillip Ocheltree, 25, said Monday that it was supposed to have been only a 12-minute drive to a safer location as storms and tornadoes struck the area of Canton, a city of 3,500 residents about 60 miles east of Dallas.

But it started hailing, "and it was already too late at that point," said his wife, Emily Ocheltree, 21. And then "the truck went sideways and spun and then flipped three times," she said.

"When we rolled, it broke one window of the door, the passenger rear door," Phillip Ocheltree said. "And that's how all the water was coming in to the cab of the truck."

Four other people were killed in the storms over the weekend.

The video of the dramatic water rescue was taken by Thomas Mitchell, who told NBC News what he witnessed was strangers' helping strangers in need. He said the car was overturned in a ditch filled with at least 4 feet of fast-moving water.

"They had no fear," he said of the rescuers. "I mean, it was no hesitation."

Mitchell, who said he, too, performed CPR on one of the children, said he thought the boy was a goner.

"I thought he wasn't coming back," he said. "His body was gray blue."

"It's not an image I can get out of my head — seeing my son's little legs dangling blue and purple when they pulled him out," Emily Ocheltree said.

Virginia Howard, who was reunited Monday with Mitchell and another rescuer, said she was the first on the scene. She believes God meant for her to be there.

"As I was coming down the highway ... all the cars were stopping trying to find shelter, getting away from the hail and stuff," she said. "And I kept hearing the Lord tell me to go, don't stop, keep going, don't stop. And my sister said, 'Pull over, y'all.' I said no, the Lord told me to keep going."

Howard said she didn't stop until she saw the stricken vehicle with the family trapped inside.

"It was terrifying," she recalled. "There was nobody around, and I could just hear them beating the window. 'Help! Somebody help us, please help us!'"

Howard said the water was moving too fast for her to approach the car. But within minutes, more help arrived, she said.

"I think it was that and the fact that there was so many people willing to get out there," she said. "Everybody seemed to be working as a team."

The children's mom had this message for the team:

"I'm very thankful. God bless you, and thank you for risking your lives to save ours."