ABC News March 16, 2018

Florida bridge collapse death toll likely to rise as investigators sift through rubble, police say

WATCH: FIU student among victims of bridge collapse

The death toll from the collapse of a brand-new pedestrian bridge near Florida International University has risen to six, including a student at the school, authorities said today.

And officials believe the number of dead may rise as investigators sift through the rubble after the search and rescue efforts were called off last night.

"There is the sad possibility that under the concrete there may be additional vehicles," Alvaro Zabaleta, a spokesman for the Miami-Dade Police Department, said at a news conference today. "The engineers are working at it in a very tactical way. The structure is fragile and could be dangerous to rescue personnel."

Joe Raedle/Getty Images
A rescue dog and its handler work at the scene where a pedestrian bridge collapsed at Florida International University on March 15, 2018 in Miami.
Joe Raedle/Getty Images
Miami-Dade Fire Rescue Department personnel and other rescue units work at the scene where a pedestrian bridge collapsed at Florida International University on March 15, 2018 in Miami.
Witness saw bridge 'collapse in front of me,' fall on cars waiting for the light: 'It was in slow motion' Florida bridge that collapsed was touted as 'engineering feat come to life'

Here is what we know about the deadly collapse:

-- The cause remains under investigation.

-- FIU President Mark Rosenberg said today on "Good Morning America" that the "project has been done as every other project at FIU in terms of construction. ... We only work with certified contractors that have been approved by all the appropriate authorities."

-- "We're shocked and we're going to cooperate fully," Rosenberg said. "We've got to get to the bottom of this and we will."

DroneBase via AP
The collapsed pedestrian bridge at Florida International University in Miami, March 15, 2018.
Roberto Koltun/The Miami Herald via AP
Emergency personnel responds to a collapsed pedestrian bridge connecting Florida International University on March 15, 2018 in the Miami area. The brand-new pedestrian bridge collapsed onto a highway crushing at least five vehicles.

-- The newly installed bridge, hailed as an engineering marvel, collapsed about 1:30 p.m. Thursday and immediately trapped at least eight vehicles, authorities said.

-- One woman who barely avoided the collapse said she saw the structure crumble "in front of me, and it fell on the cars that were waiting for the light to change."

-- "I was near the light. I was the first car that moved forward when it changed and I was near the bridge. It was fine, and all of a sudden, I saw it collapse from the left towards the middle," Suzy Bermudez told reporters Thursday. "I ran to see if we could help but the only thing we could see were the car lights in the front, totally smashed, almost to the ground."

-- Ten victims were transported to Kendall Medical and labeled as level-one trauma patients, Dr. Mark McKenney, the hospital's program director, said Thursday. They ranged in age from 20 to 50. Eight others were admitted with broken bones and bruises. Additional patients may have been admitted to other facilities.

Wilfredo Lee/AP
Police work next to a crushed car under a section of a collapsed pedestrian bridge, March 16, 2018 near Florida International University in the Miami area.
Miguel Gutierrez/AFP/Getty Images
This AFP TV video frame grab shows a newly installed pedestrian bridge over a six-lane highway in Miami on the Florida International University in Miami, March 15, 2018, crushing a number of cars below.

-- Joining local authorities on the scene are officials from the National Transportation Safety Board and FBI. In addition to ensuring the safety of those digging through the rubble, efforts are slowed because "we don't want to rush it and damage any evidence," Zabaleta said. "That bridge, whatever's left of it, is very, very unstable."

-- FIU had touted the bridge as one of the first of its kind, tweeting that it swung into place Saturday.

The Miami Herald via AP, FILE
This March 10, 2018 drone image shows an early morning view of the main span of the a pedestrian bridge while being positioned to connect the City of Sweetwater, Fla., to Florida International University near Miami.

-- Florida Sen. Marco Rubio, R-Fla., tweeted Thursday that the cables that suspended the bridge "had loosened & the engineering firm ordered that they be tightened. They were being tightened when it collapsed."

-- Rubio, who described the incident as "troubling and tragic," said the bridge was constructed for safety after a student died last year crossing that intersection.

ABC News' Kelly McCarthy contributed to this report.