DALLAS (CBSDFW.COM) – A family is in mourning after three young men were killed in a hit-and-run crash while they were changing a flat tire along LBJ Freeway early Sunday morning. Police are still looking for the driver who hit them.

According to family, Hieu Minh Doan, 23, was driving four friends after leaving a concert when their vehicle got a flat tire. That’s when Doan and two of his friends, 22-year-old Christopher Phan and 23-year-old David Nguyen, went out to fix it.

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Police said a driver in a Chevy Silverado struck the three men and their vehicle, killing them and injuring Doan’s other two friends inside the vehicle. The suspect driver is said to have fled the scene on foot.

Doan’s mother, Minh Dang, showed CBS 11 News photos of her son as he had just graduated from the University of Texas at Dallas last year with a degree in biomedical engineering.

Hieu Minh Doan (left) (Family Photo)

She spoke in her native Vietnamese and had a friend, Andy, help translate.

“She’s in shock and saddened right now that the news happened to her oldest son,” Andy said.

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The crash happened at around 3:30 a.m. after Doan, Phan and Nguyen went out to fix the flat tire.

“He was always one of these people who wanted to take care of his friends any way he can. I guess that’s what he was going. The flat tire. ‘I’ve got this. I’ll change this,'” Andy said for Doan’s mother.

Doan’s family is wanting to know how the crash happened as the suspect ran away from the scene. Police said the driver also left a 13-year-old boy inside the pickup truck. He was taken to the hospital where he met with his mother.

Police have not released any further details on the suspect driver.

“She’s not angry at anybody, and she’s not mad that he’s not caught or still out there. She’s willing to forgive that person if they were to be caught, but she just wants to say it’s unfortunate that these things can happen at night,” Andy said for the mother.

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“He had so much potential and so much life to live. He just finished school. He had a bright future ahead of him,” he added.