Moments before a Florida pedestrian bridge crumbled in a pile of metal and concrete, Isabella Carrasco drove under it.
Then she heard a loud boom as the recently installed bridge collapsed near Florida International University on Thursday, killing at least six people.
"The cars were completely crushed under it," she said.
"Quite frankly, I'm lucky to be alive. That could have easily been me and my boyfriend under that bridge had we not turned right and decided to stay at the light and gone a different direction."
Carrasco was one of several drivers and pedestrians who were near the busy intersection Thursday. Some saw the bridge turn to rubble in front of their eyes.
It "sounded like a bomb, like multiple bombs in one," Giovanni Hernandez told CNN affiliate WSVN. "It sounded like the world was ending, and when you look back, all you see is the bridge on the floor. It was awful."
Lynell Collins, who drove past the bridge frequently, helped pull people from crumpled cars.
"After the whole thing broke, I was freaking out," Collins told CNN. "I got out of my car, and me and a few other people were sprinting over there. We started helping people whose cars were at least half crushed and whoever was easily saved. But we couldn't really go under any of the rubble because, at the time, the bridge -- the other half of the bridge is still kind of leaning upward right now."
Collins said one of the victims said his family was beneath the rubble, and we couldn't help get them out.
"I'm sorry. I'm still shaken right now," he said.
Some first responders closed off the street and others tended to the injured with the help of medical students. A police officer shook her head when someone asked if she'd heard any response from people inside one car, Carrasco said.
Aura Martinez and her mom were getting food at a nearby restaurant when they turned around and realized the bridge had collapsed.
The FIU student said she initially didn't know what to do, but then her instincts kicked in.
"We ran out there and we tried to help people," Martinez told CNN affiliate WFOR.
The bridge was built to connect the school's campus to the adjoining Sweetwater neighborhood, where many FIU students live.
"I was shocked because this thing they built, it had so much potential and everything, but it just literally killed people," she added.