It happened on Highway 6 near County Road 925.
Taylor Broussard's parents say doctors have told them their daughter likely has brain damage.
"She's basically in there fighting for her life," said Shelly Vincent, Taylor's mother.
Taylor's parents spoke to ABC13 about Taylor's injuries.
"It looks like she was in a boxing ring. Her face is torn up. All the bones in her face are broken, her clavicle is cracked, her arm is broken, legs are broken, her ribs are broken," said Sean Broussard, Taylor's father.
Authorities say the teen was standing in a moving lane of traffic when she was hit.
According to her parents, Taylor was in her boyfriend's car and the two got into a fight. He pulled over and Taylor got out. Sean thinks she may have been on her phone, distracted.
"She could've not seen it (the truck) or maybe it swerved at the last second, who knows," he said.
The driver who hit Taylor stopped to help and cooperated with Brazoria County sheriff's deputies.
The driver showed no signs of impairment, deputies say. Speed is not believed to be a factor in the crash.
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