Two cars have been removed from underneath the pedestrian bridge that collapsed near Florida International University, according to the Miami-Dade Police Department.

Three bodies were recovered from the two vehicles, officials said during a news conference Saturday morning. As of now, the death toll remains at six as officials work to extract six more cars from beneath the rubble.

Miami-Dade police have identified four of the people killed: Rolando Fraga Hernandez; Oswald Gonzalez, 57; Alberto Arias, 53; and Navarro Brown.

The vehicles removed Saturday morning were completely flattened after the 950-ton bridge fell. The cars were transported to the Miami-Dade County Medical Examiner’s Department, according to the MDPD.

Authorities said Friday there could be more fatalities beyond the six deaths already confirmed in the collapse of the 174-feet concrete structure. As state and federal investigators worked to determine how and why the five-day-old-span failed, Miami-Dade Police Director Juan Perez told reporters at a Friday news conference he expects additional victims to be found.

Authorities identified one of the victims Friday: Alexa Duran, an 18-year-old FIU student. NBC News reported that Duran was driving home from a doctor's appointment when the bridge collapsed on top of her car. Her best friend, Richard Humble, was in the passenger seat when it happened. He told the "Today" show that he and Duran had been at a red light when they heard a creak above them, just seconds before the bridge crushed their car.

Humble said that it happened too fast for them to duck out of the way. He suffered a neck injury but was able to walk away, he told "Today."

He told NBC News that although he feels "very grateful to be alive," he doesn't "feel so lucky right now."

People who haven't heard from their loved ones congregated near the scene Friday.

Jorge and Carol Fraga drove from West Palm Beach, fearing their relative's car was trapped beneath the bridge at Florida International University. Sixty-year-old Rolando Fraga, Jorge's uncle, lives in the area and frequently takes the nearby turnpike to work, but no one has heard from him since mid-day Thursday.

"The waiting is so ... I don't have words for that," Carol Fraga said through tears.

Experts from the National Transportation Safety Board and the Occupational Safety and Health Administration joined police in taking over command of the scene Friday from first responders, who had spent hours racing to find survivors in the rubble of the 175-foot span using high-tech listening devices, trained sniffing dogs and search cameras.

Perez and Miami-Dade County Fire Chief Dave Downey said the decision to transition from a rescue to a recovery mission was made around 10 p.m. Thursday.

"We are working with local officials, but we are conducting a separate investigation from criminal charges," said NTSB Chairman Robert Sumwalt III.

Perez said that the Miami-Dade State Attorney's Office is on the scene investigating as well, but warned against jumping to conclusions.

"This is a tragedy that we don't want to re-occur anywhere in the United States," Perez said. "We just want to find out what caused this collapse to occur and people to die."

Ten people were transported to Kendall Regional Medical Center from the site of the collapse near Southwest 8th Street and 109th Avenue. Two were listed in critical condition when they arrived and one person died at the hospital. Officials have not confirmed if the deceased was one of the 10 taken there or if it was someone who was brought in themselves.

"Fire and us, we prepare for mass casualty events, but never a collapse like this," Perez said in an interview with radio station WIOD-AM on Friday.

The bridge was reportedly put to a "stress adjustment" before it collapsed over traffic before 2 p.m. on Thursday. Two workers were on top when it pancaked on top of vehicles waiting at a stoplight.

Perez and Miami-Dade County deputy mayor Maurice Kemp would not confirm if that test did take place.

Sgt. Jenna Mendez of the Sweetwater Police Department was one of the first responders on the scene. The collapse happened while she was driving to work and she said she only missed becoming a victim herself because she had been running late and was stopped at a red light when the disaster struck.

“I really wasn’t believing what I had seen,” she told NBC's "Today" show on Friday.

Mendez said that after realizing what had happened she jumped on top of the bridge to help construction workers who were "severely injured."

"I was just in that rescue mode," she said. Fire rescue officials had to yell at her not to put her safety at risk by going under the debris.

One factor in the tragedy may have been that adjustment that Miami-Dade Mayor Carlos Gimenez said crews were conducting on the span.

U.S. Sen. Marco Rubio tweeted late Thursday that the cables that suspend the bridge had loosened and the engineering firm ordered that they be tightened. "They were being tightened when it collapsed," he said on Twitter.

The $14.2 million pedestrian bridge was supposed to open in 2019 as a safe way to cross the busy six-lane road between the university campus and the community of Sweetwater, where many students live.

A family reunification center is located on the campus of FIU in the Student Academic Success Center Room 100. Families were advised to access the building via SW 16th Street and 107th Avenue or call 305-348-3481.

At the accident scene, Florida Gov. Rick Scott said investigators will get to the bottom of "why this happened and what happened," and if anyone did anything wrong, "we will hold them accountable."

Rubio, who is an adjunct professor at the school, noted the bridge was intended to be an innovative and "one-of-a-kind engineering design."

Renderings showed a tall, off-center tower with supporting cables attached to the walkway. When the bridge collapsed, the main tower had not yet been installed, and it was unclear what builders were using as temporary supports.

An accelerated construction method was supposed to reduce risks to workers and pedestrians and minimize traffic disruption, the university said. The school has long been interested in this kind of bridge design; in 2010, it opened an Accelerated Bridge Construction Center to "provide the transportation industry with the tools needed to effectively and economically utilize the principles of ABC to enhance mobility and safety, and produce safe, environmentally friendly, long-lasting bridges."

The project was a collaboration between MCM Construction, a Miami-based contractor, and Figg Bridge Design, based in Tallahassee. Figg is responsible for the iconic Sunshine Skyway Bridge across Tampa Bay.

Figg's statement Thursday said the company was "stunned" by the collapse and would cooperate with investigations.

"In our 40-year history, nothing like this has ever happened before," the statement said. "Our entire team mourns the loss of life and injuries associated with this devastating tragedy, and our prayers go out to all involved."

MCM Construction Management promised on its Facebook page to participate in "a full investigation to determine exactly what went wrong."

The FIU community, along with Sweetwater and county officials, held a "bridge watch party" on March 10 when the span was lifted from its temporary supports, rotated 90 degrees and lowered into what was supposed to be its permanent position.

FIU President Mark Rosenberg said the bridge was supposed to be about "goodness."

"Now we're feeling immense sadness, uncontrollable sadness," he said. "And our hearts go out to all those affected, their friends and their families. We're committed to assist in all efforts necessary, and our hope is that this sadness can galvanize the entire community to stay the course, a course of goodness, of hope, of opportunity."

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This story is courtesy of our news partners at NBCMiami.com.

NOTE: This story has been updated to reflect that the current number of fatalities remains at 6, not 9 as previously reported.