(CNN) Hours before a pedestrian bridge collapsed at Florida International University last year, engineers said cracks in the structure didn't pose a safety concern, according to an Occupational Safety and Health Administration report.

The March 2018 collapse -- which killed six people -- could have been prevented, OSHA said in the 115-page report released this month.

Growing cracks in the structure warranted an immediate closure of SW 8th Street, the street onto which the bridge collapsed, the report said. But the bridge's designers, FIGG Bridge Engineers, after inspecting it that day, said the cracks did not pose any safety concerns, according to the report.

She drove under bridge moments before collapse

She drove under bridge moments before collapse 02:06

She drove under bridge moments before collapse

Urgent, but dismissed, concerns

FIGG Bridge Engineers knew that "numerous wide and deep structural cracks" had developed and lengthened daily, but dismissed them, the report says. The document contains multiple texts and emails from crew members concerned about the growing cracks.

One crew member sent his supervisor a text message with a picture of a construction joint with cracks running through it in multiple places.

"It cracked like hell," the crew member wrote in the message.

A senior project manager also expressed concern over the cracks in an email with photo attachments.

Despite what OSHA said in the report was "a sense of urgency" from the workers, FIGG did not treat the matter as urgent.

FIGG Bridge Engineers said in a statement to CNN that they reviewed the report and disagreed with OSHA's conclusions.

"The OSHA FIU Pedestrian Bridge report is factually inaccurate and incomplete, and includes errors and flawed analyses. It does not include an evaluation of many important factors pertinent to the construction process leading up to the accident," the statement reads. "Additionally, it has not been reviewed by any other entities involved in the accident investigation."

"FIGG disagrees with the conclusions in the OSHA report," FIGG said, adding that that it could not elaborate further because the incident is being reviewed by the National Transportation Safety Board.

The report also said that the bridge's contractor, Munilla Construction Management, failed to address safety concerns that morning.

Munilla Construction Management told CNN that it is reviewing OSHA's report.

"Our company fully cooperated with OSHA's investigation from Day 1, and we appreciate their efforts. If MCM determines that any of the information contained in the report should be supplemented, we will bring it to OSHA's attention immediately," the company said in an emailed statement.

When reached by CNN on Tuesday, a Florida International University spokeswoman, Madeline Baró, said the university wasn't in a position to comment on the report, citing an ongoing investigation by the National Transportation Safety Board.

Photos: Photos from the scene: Pedestrian bridge collapses in Miami Emergency personnel respond to a deadly bridge collapse in Miami on Thursday, March 15. The bridge was installed Saturday at Florida International University. Hide Caption 1 of 12 Photos: Photos from the scene: Pedestrian bridge collapses in Miami A rescue dog searches for victims after the bridge collapsed. Hide Caption 2 of 12 Photos: Photos from the scene: Pedestrian bridge collapses in Miami Miami residents watch rescue crews work to remove victims from the debris. Hide Caption 3 of 12 Photos: Photos from the scene: Pedestrian bridge collapses in Miami The president of Florida International University, Mark Rosenberg, speaks to reporters with Florida Gov. Rick Scott behind him. Rosenberg said FIU followed required processes during the bridge's construction and all contractors were certified by the state. Hide Caption 4 of 12 Photos: Photos from the scene: Pedestrian bridge collapses in Miami A rescue dog and its handler work at the scene of the collapsed pedestrian bridge. At least six people were killed. Their identities were not immediately released as authorities worked to contact family members, Miami-Dade Police spokesman Alvaro Zabaleta said. Hide Caption 5 of 12 Photos: Photos from the scene: Pedestrian bridge collapses in Miami Crews work at the scene. The structure's 950-ton main span had just been installed Saturday using an accelerated construction process meant in part to reduce the time that street traffic was halted. The bridge had been designed to withstand a Category 5 hurricane. Hide Caption 6 of 12 Photos: Photos from the scene: Pedestrian bridge collapses in Miami Rescue teams look for victims in cars trapped in the rubble. Hide Caption 7 of 12 Photos: Photos from the scene: Pedestrian bridge collapses in Miami Multiple agencies responded to the scene. A spokeswoman with Miami-Dade Fire Rescue told CNN there were multiple injuries. Hide Caption 8 of 12 Photos: Photos from the scene: Pedestrian bridge collapses in Miami Candace Pridemore took this photo of the collapsed bridge. "I was sitting in a truck," she said. "We were pulled over to the side working. I looked over and there was a bridge coming down. I started screaming, 'It's going, it's going down.'" Hide Caption 9 of 12 Photos: Photos from the scene: Pedestrian bridge collapses in Miami Police block a road near the collapsed bridge. Hide Caption 10 of 12 Photos: Photos from the scene: Pedestrian bridge collapses in Miami According to a fact sheet about the bridge on FIU's website, it cost $14.2 million to build and was funded as part of a $19.4 million grant from the US Department of Transportation. It was designed to withstand the strength of a Category 5 hurricane, the fact sheet said, and it was supposed to last for more than 100 years. Hide Caption 11 of 12 Photos: Photos from the scene: Pedestrian bridge collapses in Miami Emergency personnel work at the scene. Hide Caption 12 of 12

Built for safety

Beyond the response to the cracks before the collapse, the report said there were missteps throughout the construction process, citing a "deficient" design and inadequate oversight by engineering consultants that violated requirements by the Florida Department of Transportation.

The university, located in Miami, Florida, commissioned the $14.2 million bridge to connect the school's campus to the Sweetwater neighborhood, where thousands of students live.

The footbridge had been built to avoid tragedy, after an 18-year-old student at FIU was killed after being hit by a vehicle while crossing a nearby street.

It was intended to be strong enough to withstand a Category 5 hurricane and last 100 years, the university said in a fact sheet

It was also designed using Accelerated Bridge Construction which makes the construction quicker and cheaper and also keeps the street from being blocked for long periods.

CORRECTION: An earlier version of this story incorrectly attributed a statement criticizing OSHA's report. That statement was released solely by FIGG Bridge Engineers.