Hayne Rucker and Aaron Stephens said they had been checking out their purchases near the front of the Walmart when they heard a loud bang that echoed through the aisles. Two gunshots followed, and then three or four more in quick succession, they said.
âI just tore toward the door,â Mr. Rucker said.
Gonzalo Benitez, a construction worker, said he had been buying food for his family when he heard six or seven gunshots and customers began screaming.
âA lot of people crying, running fast,â Mr. Benitez, 44, said. âI see a couple of people on the floor.â
He and other customers rushed through the aisles to a rear exit door, he said, and had to pound against it to force it open.
Even as the Thornton police warned people to stay away from the crime scene, some frantic family members showed up to seek word about loved ones who had been working or shopping there when the shooting began.
The Walmart is part of the Thornton Town Center, a shopping complex steps from Interstate 25 in Thornton, a city of about 136,000 in the suburbs north of Denver. Outside the store, next to chain restaurants, apartment complexes and home supply stores, family members of shoppers and employees gathered across the street to wait for a sign of their loved ones.
âMy brother is somewhere in there, and he doesnât pick up,â said Maria Martinez, 19, as she walked around the flashing police cars blocking the entrance to the Walmart parking lot.
She said that her brother, Ignacio, 27, had gone to buy diapers for his three children, and that the family had been frantically texting and calling him since they heard about the shooting.
Mr. Rucker said the terrorist attack in Manhattan on Tuesday and other mass shootings in public places â like a music festival in Las Vegas, an Orlando nightclub and a movie theater in nearby Aurora, Colo. â had injected a sliver of fear into ordinary errands like running out to the Walmart for groceries.
âYou canât get that out of your mind,â he said. âWhen youâre in a public place and you hear gunshots, thatâs kind of the first thing that comes to your mind: Here we go again. Looks like this time, we are potential targets.â