CERES (CBS13) – A gas pump burst into flames after a driver suspected of DUI came flying off Highway 99.

The driver has been identified as 23-year-old Isabel Zepeda, who, the CHP says, had a 4 and 5-year-old in the backseat.

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Surveillance video shows Zepeda veering off the freeway while another woman ran out of the way to safety.  A family right next to the pump that caught fire barely avoided getting hit.

So why didn’t the crash cause a massive explosive?

“So, these are called the shear valve,” said service technician Joe Bartholdi.

He says each pump has a weak point in its piping that breaks off on purpose when necessary. It’s part of its safety system and did exactly what it was supposed to do at that moment.

“So, if it gets hit it shears off at a certain point here, so it breaks there and then these shut it off,” he explained.

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Isabel Zepeda (credit: Stanislaus County Sheriff’s Office)

The safety system prevents fuel from spraying out of the ground.

“As soon as this breaks, they did their job,” Bartholdi said.

“I was just thinking this whole station was going to go up in flames,” said Roy Spears.

Spears was pumping gas right before the fiery crash and is grateful for the safety system that prevented what could have been an even more dangerous situation.

“Just unbelievable, unbelievable,” he said.

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Zepeda was charged with DUI and child endangerment. The children suffered minor injuries and are doing OK, according to the CHP.