A pedestrian bridge under construction in the Miami area collapsed suddenly and without warning Thursday afternoon, killing at least four and injuring ten. Rescue crews continued to dig through the rubble in search of survivors Thursday evening.

Eight or more cars with passengers inside them were instantly crushed and others remain trapped under the rubble after the bridge, which had been prefabricated and set in place by cranes just last Saturday, fell on six lanes of the Tamiami Trail road while drivers waited at a red light.

Witnesses described a chaotic scene as nearby residents rushed to help. Some motorists whose vehicles had only been half crushed were seen crawling from their wrecked cars. Doctors and nurses from a nearby hospital rushed to the scene by foot to come to the aid of the injured. Ten people have been admitted for injuries so far.

The Florida Highway Patrol told the Miami Herald they were unsure how many may still be trapped under the collapsed bridge. News helicopters were reportedly asked to stay away from the scene so first responders could listen for survivors.

Even though it was not due to open to pedestrian traffic until 2019 witnesses reported that there were workers present on the bridge before the collapse. It is unknown at this time if they are included in the casualties.

The footbridge, which was to connect the suburban community of Sweetwater with Florida International University (FIU) in Miami, was to have a length of 320 feet. The main 175-foot span, weighing some 950 tons, was built on the side of the road over a period of months while support towers on either side of road were constructed.

The bridge was lifted into place over the weekend by cranes in a building method engineers call “accelerated bridge construction” and was described as “innovative” by the builders and by FIU. The entire process was said to take six hours. In an article published last weekend describing the construction, the Herald quoted FIU officials as saying, “The innovative installation method significantly reduced risks to workers, pedestrians, and motorists and minimized traffic disruptions.”

As of this writing, the cause of the collapse is unknown. The Herald cited unconfirmed reports that stress tests were being performed on the bridge at the time of the accident.

According to the Herald, the footbridge connecting FIU with the community of Sweetwater was a long sought-after project for residents and students. The bridge was also part of FIU’s so-called “prosperity” project, intended to revitalize downtown Sweetwater and relieve traffic congestion.

Upon its opening, the bridge would have directly linked the school to several large apartment complexes recently built by private developers in Sweetwater as part of the project. According to the Herald, the new bridge would have led directly to an 895-unit building due to break ground in June.

Approximately 4,000 FIU students already living in Sweetwater have to cross the busy Tamiami Trail to reach the university. In August, a student was struck by a car and killed while crossing the road.

Constructed at a cost of $14.2 million, the bridge was funded by the US Department of Transportation, designed by FIGG Bridge Group and built by MCM Construction. The engineering firm BDI was responsible for monitoring and performing safety inspections on the project.

Twitter users took note of the fact that after the accident, BDI quickly deleted a tweet posted last weekend stating “We are thrilled to have performed structural monitoring during a bridge move by #BarnHartCrane at#FIU #Miami. Congratulations to BCR on a job well done. We always appreciate being part of the team!” FIU similarly deleted a story from their website describing the bridge’s construction.