Constable Ted Heap identified the Harris County Precinct 5 as 46-year-old Katherine Hutson. Her daughter, Kacey, was just 7 years old.
All westbound lanes of the freeway at the IH-610 West Loop were shut down for eight hours. The road reopened at about 11 a.m.
The three-vehicle crash happened at 3:07 a.m. Police said a Mazda crashed into Hutson's car, and a utility truck was parked on the shoulder. All three vehicles instantly burst into flames.
Houston TranStar cameras showed large flames at one point as emergency crews responded.
HPD said a worker who was standing outside of the utility truck was taken to the hospital in stable condition with burns. A female passenger in the Mazda was also taken to the hospital.
Investigators said the driver of the Mazda was not hurt and stayed at the scene to cooperate with investigators.
After running toxicology and DWI tests to determine if impairment was a factor in the deadly crash, police found the at-fault driver to be impaired.
"Constable Ted Heap, along with his deputies and staff, mourn the loss of Deputy Katherine Hutson and her daughter Kacey, whose lives were lost when they were struck by a suspected drunk driver on the Katy Freeway this morning," the constable's office shared on social media.
According to Heap, Hutson was an 18-year veteran of the agency. She had been with Pct. 5 since 2006, serving in patrol, parks, toll road, and, most recently, civil division.
She was a single mother working an extra job, providing a police presence for road improvements, Pct. 5 said.
"Katherine was a loving and caring mother as well as a dedicated deputy," Heap said. "She was a friend to many in our department, and her smile and upbeat personality will be dearly missed. I ask you all to keep her family and loved ones in your prayers."
The Houston Police Department is investigating the crash.
"I do ask Houstonians to please pray for these families, especially with the holidays coming up," Asst. Chief Adrian Rodriguez said. "This is a very tragic scene that we have, and our hearts and prayers go out to the individuals that were lost and their family members who are going to have to deal with this tragic scene."
The Harris County District Attorney's Office is also looking into possible criminal charges.