The Harris County Sheriff's Office is investigating a traffic stop that preceded a fiery crash caused by a suspected impaired driver.

The crash happened just before 9 p.m. on Sunday. A mother and her three children, ages 7 months, 2 years old, and 5 years old, were stopped a red light when another driver crashed into the back of the family's car. The crash caused a 7-car pileup and left the family's car engulfed in flames.

According to KTRK, the Harris County Sheriff's Office said the driver, identified as Daniel Canada, was stopped shortly before the fiery crash by one of its deputies for speeding.

"The deputy had the driver exit the vehicle and briefly detained him. The driver told the deputy he had a small amount of marijuana in the vehicle, which the deputy took into evidence," the sheriff's office told KTRK.

However, due to Canada not showing any signs of outward impairment, the deputy released him following the traffic stop.

The family was killed in the wreckage less than an hour later.

Investigators say that the 7-month-old, 5-year-old, and the children's 28-year-old mother were killed instantly. The 2-year-old was taken from the accident scene to an area hospital via Life Flight and placed on life support.

He succumbed to his injuries on Monday.

According to the Texas Department of Transportation, you are legally intoxicated under state law when your blood alcohol concentration reaches 0.08%. However, you're still considered to be breaking the law as soon as drugs or alcohol affect your driving.

Canada was found to have a blood alcohol level of 0.15% at the time of the crash. He faces three counts of intoxication manslaughter. Another is likely to be added following the 2-year-old's death.

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