A witness to an alleged drunken driving crash in which an off-duty Dallas firefighter killed a pregnant 18-year-old girl and her unborn son told investigators the man’s sports car exceeded 100 mph moments before the fatal collision. The firefighter, identified by police as Horace Shaw III, 45, has been charged with intoxication manslaughter in the death of Alyssa Pimentel, of Midlothian. Shaw was driving a Mercedes-Benz sports car around 12:45 a.m. Wednesday in Cedar Hill when he rear-ended the Mazda SUV Pimentel was driving. Pimentel and her boyfriend, Isaiah Perez, were both ejected from the vehicle. Pimentel died at the scene, according to investigators. Perez, 21, suffered a broken neck and broken leg, according to the Dallas-Fort Worth NBC affiliate. Perez spoke to the news station about losing his girlfriend and son. “I sure do miss her. I’d give my life to her just to bring her and my son back,” Perez said. He said that, although he does not remember the crash, he recalls waking up afterward and seeing Pimentel on the ground, dying. “I ended up crawling to her,” Perez said. “The next thing you know, she said, ‘I love you,’” and just keep your head up. I was promising her nothing would happen.” Pimentel was conscious and talking for a few minutes, but died as paramedics arrived. The couple were taken to separate hospitals. Perez later learned that doctors delivered their son, but the baby lived just a few minutes, the news station reported. The couple planned to name him Josiah Adrian Perez. An arrest affidavit in the case, obtained by the news station, states that a witness told Cedar Hill police investigators that he was driving south on U.S. Highway 67 when he was passed by a white Mercedes sports car, which authorities determined Shaw was driving. “The witness stated that the defendant’s vehicle passed him at what appeared to be between 100 to 110 mph,” the affidavit read. “When the defendant’s vehicle crested a hill on the highway, the witness saw sparks and could also see two vehicles, one being the defendant’s vehicle, slide onto the grassy shoulder between the highway and the southbound service road.” The witness stopped at the crash scene to offer aid and encountered Shaw, the document said. “When the witness stopped and approached the vehicles, the defendant got out of his vehicle, walked to where the driver of the second vehicle was laying on the ground, told the witness he was a paramedic, then laid on the ground,” the affidavit said. Shaw avoided talking with police officers on the scene, the court document said. The officers found an empty metal flask, which smelled of alcohol, in Shaw’s car. >> Read more trending news A second witness told investigators that Shaw also passed her at a high rate of speed about 30 seconds before she came upon the crash scene. She said when she got there, Pimentel was lying on the entrance ramp to the highway, appearing unconscious. “The witness stated that the defendant appeared to be intoxicated and explained how she observed the defendant was unable to walk straight when he exited his vehicle,” the affidavit said. Investigators said Shaw’s passenger told them that the pair had been coming from a restaurant in Dallas where they had been drinking. He admitted that Shaw was “speeding a little bit” when the crash occurred. When asked if Shaw was “showing off,” the man said he was, the affidavit said. The man became uncooperative when asked further about their drinking, but the officers said they smelled the strong odor of alcohol on the man’s breath. They also smelled alcohol on Shaw, who refused to answer questions and asked for an attorney, the affidavit said. Pimentel’s parents, Joe and Jayne Pimentel, released a statement Wednesday afternoon in which they asked for prayers and privacy. “We are currently shaken and saddened by the tragic events that occurred today. Alyssa was our one and only daughter carrying our grandson, with their whole lives ahead of them,” the statement posted to Facebook read. “We are very disappointed with the fact that an individual who is tasked with saving lives is responsible for taking the lives of our family members. “As you can imagine, our grief right now is immeasurable. We are aware that there is an investigation into the accident and we trust that the authorities will be diligent in seeking justice for Alyssa and Baby Josiah.” Shaw was released on $45,000 bail Wednesday from the Dallas County Jail. Investigators said he could face additional charges.