Jenna Mendez was driving to work at the Sweetwater Police Department, where she’s a sergeant in the criminal investigations bureau, when she got caught by a red light at an intersection near Florida International University.

“I’m going to be here forever,” she thought on Thursday. It’s always a slow one, with so much traffic from FIU.

As she waited, she saw a new pedestrian bridge crash onto the road ahead of her, sending a great cloud of dust rising up.

She didn’t understand what she had just seen. It made no sense. Bridges don’t fall on roads.

In shock, she turned her car’s lights and sirens on, thinking someone needed to shut the road down. It was only when she drove forward that she realized: “They didn’t do this intentionally. This thing just collapsed.”

And then she could see the cars trapped underneath. “I freaked,” she said, and jumped out of her car.

Somehow — she’s still not sure how — she jumped or climbed onto the bridge, where four construction workers were badly hurt. Two were unconscious. A bystander started doing chest compressions, and as Mendez helped, she screamed down to the crowd gathering below. “I need help! I need anybody to find me find first-responders, doctors, nurses. I need help up here!”

The crowd helped a woman up onto the bridge — she was a doctor at FIU, she said. And the sergeant, the doctor and the bystander took turns doing chest compressions. Mendez began seeing officers she knew and called out to them, “Over here! Over here!” They weren’t sure where to go first, she said. “There was tragedy everywhere.”

She told them they needed rescue help up there; they had one person not breathing and another with a brain injury. People threw a couple of backboards up so they could get the workers stabilized and get them down.

The other two construction workers couldn’t speak, she said; they were glassy-eyed, in shock. She was not fully herself, either — she knows now it was very loud and chaotic there, with horns honking and people screaming, but she didn’t hear it at the time.

An officer lifted her down off the bridge, and she saw a gray Toyota SUV that was half-smashed. She knew immediately the driver had not survived.

But she could see a passenger desperately trying to get out; his side of the vehicle had not been hit as hard. With a piece of wood, people pried open a back door and they were able to pull him out.

The bridge landed on the hood of another car, with a husband and wife inside. But their doors popped open, and they got out quickly, she said.

She started crawling under the bridge to get to vehicles there.

Jenna Mendez (Photo courtesy of Jenna Mendez)

“I’m a mother of five,” Mendez explained. Her oldest is 21, her youngest is 3.

“I was thinking, ‘What if there are babies in there? What if there are kids in there?’ ”

Fire-Rescue officers screamed at her to get out from under the bridge — it was much too dangerous to be there.

That snapped Mendez back to reality. She couldn’t possibly open the doors of other vehicles that were trapped. She couldn’t lift concrete. And it seemed obvious to her then that there could not be survivors underneath all that weight.

“I was in that rescue mode,” she said. “Afterward you think, ‘What the heck did I just do?’”

She tried to comfort an FIU student who was a passenger she had helped escape from the gray Toyota SUV; the student had realized he had just lost his best friend, she said.

When she was driving home late that night to see her family, it all hit her, the fragile space between life and death. Inches separated the two.

“If I didn’t get caught at that red light,” she said, “it would have been me.”