UPDATED | December 14, 2017  11:04 AM

CEDAR HILL (CBSDFW.COM) – The arrest warrant for a Dallas firefighter charged with intoxication manslaughter after a crash that killed a pregnant teenager and her unborn child details what witnesses saw before and after the accident.

Drivers on Highway 67 told police that in the early morning hours of December 13 they saw a white Mercedes Benz traveling at what appeared to be more than 100 mph. Two people were inside that car — a passenger and driver Horace Shaw III, a firefighter who was off-duty at the time.

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Witnesses say the car crested a hill and crashed into a Mazda SUV carrying pregnant teen Alyssa Pimental and passenger Isaiah Perez, both of whom were thrown from the vehicle.

Horace Shaw (credit: Dallas County Sheriff’s Department)

At least two people told investigators that Shaw appeared intoxicated and “wasn’t able to walk straight” after the crash. Officers later found a metal flask, that they say smelled of alcohol, in the car he was driving.

The passenger in the car with Shaw told police the two had just left a restaurant and bar in Duncanville where they had been drinking. The man also said Shaw was showing off and “speeding a little bit” before the crash. Officers said that passenger, who has not been identified, also smelled of alcohol.

Pimental was taken to Charlton Methodist Hospital but both she and her child died.

Shaw was taken to Methodist Central Hospital where he was advised of his rights, declined to answer questions and requested an attorney.

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At a Meals on Wheels charity event this morning Dallas Fire Rescue Chief David Coatney had no comment about the charges Shaw is facing, but offered his condolences to the families. “Our thoughts and our prayers are with the family of those lost and people that are struggling with that [deaths], that’s pretty much it at this point while the investigation continues,” he said.

Isaiah Perez (credit: CBSDFW.COM)

Hours after the crash Perez told CBS 11 News that Pimental was the “love of his life” and talked about the baby they were expecting to welcome into the world by Christmas. Perez has a broken leg and a fractured neck but was released from the hospital on Wednesday night.

“I didn’t feel it,” he recalled. “I just woke up on the ground, like somebody hit you on the back of the head.”

Pimental’s family asked for privacy during this difficult time, but released a statement on Wednesday saying that their grief is immeasurable. They were also disappointed to hear that authorities arrested a firefighter for possibly being drunk behind the wheel and causing the horrible crash.

Alyssa Pimental & Isaiah Perez (credit: Pimental Family via Facebook)

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Shaw has been with Dallas Fire-Rescue for 12 years, but has been placed on administrative leave. He was booked into the Dallas County Jail but has since been released on bail.