Lewis Matos was sitting behind his desk at AAMCO Transmissions on May 26 when the building was hit.
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Exclusive surveillance video obtained by Eyewitness News shows Matos sitting in a chair when a car crashes through the building.
SEE MORE: Daughter witnessed carjacking suspect kill mother in E. Houston, prosecutors say
The impact knocked Matos from his chair and pushed the drywall, windows and debris on top of him.
"I started to hear gunshots," said Matos.
He later learned he was caught in the middle of a carjacking.
According to police, Juan Mendez and Jaritza Chavarria were behind the carjacking. After crashing into the building, investigators say Mendez tried to shoot the victim.
"Here I was laying on the floor in horrific pain. I was pinned by this desk," said Matos.
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Matos found himself in the same area Wednesday afternoon as he looked out across the street to find a man trying to force a woman out of her car.
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"I jumped in my car, (I) didn't even think. All I kept thinking was 'he's not getting away.'"
The woman was 41-year old Jessica Garza, and police say it was Marcus Brock who carjacked her.
As Matos followed behind, he witnessed the mother of three trapped by her seatbelt, hanging from the drivers side, being dragged to her death. The car eventually crashed into a shed.
"I was mortified. When I picked up that piece of signage that was on top of her in the car, and I saw what he did to her, I was enraged," said Matos.
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Matos, devastated he couldn't stop the man before Garza was murdered, continued to search for him to ensure he wouldn't get away.
"It gets kind of tedious watching everybody always getting away," Matos said.
Matos found Brock in a nearby liquor store and kept him from leaving until police arrived.
"You don't have to put yourself in harms way, but be more vigilant. Keep an eye on your neighbors, your friends and help"
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