(CNN)Sweetwater police Sgt. Jenna Mendez saw the pedestrian bridge fall onto 8th Street next to Florida International University on Thursday -- but it made so little sense, she first thought a demolition crew intentionally collapsed it.
This officer missed the bridge collapse by seconds. Then she scaled the rubble to save the injured
"Why would they have brought the bridge down during the day?" she thought as it fell in front of her, as she was stopped at a red light just one intersection away.
Then she realized cars had just been crushed. Her confusion was over: "This was not on purpose; this was a catastrophe," she said.
Mendez -- had she beaten that red light -- might have been one of the victims of the collapse, which killed at least six people. Instead, she was a both a witness and one of the first people to reach the injured in the critical moments after their trauma.
Mendez, back at the scene in uniform on Friday morning, spoke to CNN about the chaos of Thursday. She jumped out of her vehicle, she recalled, and her instinct and training took over.
"I saw on top of the (rubble), there were several construction workers that were injured very badly. I jumped up there to assist, and I had four guys laying there," she said.
Two men had broken bones, and two others were unconscious -- one who wasn't breathing and the other with a major cut to this head. Mendez started chest compressions on the one who wasn't breathing, she said.
"I started yelling to civilians in the crowd, 'Please get me doctors. ... I need help up here.' A doctor jumped up, and she started helping," Mendez said.
Rescue workers arrived with patient backboards, and the two unconscious people were taken to a hospital, Mendez said.
Officers and others rushed to an SUV that was partially crushed underneath. The driver was killed, but the passenger was rescued, Mendez said.
"They were able to take a piece of wood, and civilians (and) officers pried that door open and pulled him out of the back seat of that car," she said.
She was so shocked, she says, she doesn't remember hearing the collapse.
"When I look back and see the news stories, you obviously can hear all the horns and the chaos, and think I was in such a zone and a mode that I do not remember hearing anything, to be honest with you," she said.
One of the sounds she does remember: crying.
"We were trying to comfort (the survivors)," she said. "They were all pretty much in shock. Nobody was talking to us or answering our questions. We were aware that they were in shock, so we just kind of waited a good 15 minutes for them to start coming out of it and realizing what was going on.
"They started crying, and they came to."
The survivors eventually talked.
"Just saying, 'Oh my God, it crushed our car, and we're alive,'" she recalled. "The other gentleman was saying his best friend, she was in the car, and, 'She didn't make it, oh my gosh.' And he was crying.
"I tried to comfort him as much as possible."
A mother of five, she was thankful she was able to tell her own husband later that she was OK.
"I was seconds away from being caught under that," she said.