A pedestrian walkway that was still under construction collapsed onto a busy highway in Miami on Thursday, killing at least six people.

The Florida Highway Patrol said multiple vehicles were crushed by the span near Florida International University's campus when it came down at around 1:30 p.m. According to Miami-Dade County Fire Rescue, there were workers on the bridge and several cars underneath.

At a press conference Thursday evening, Miami-Dade Fire Chief Dave Downey said that at least six people were killed by the collapse. The deceased have not been identified. Rescue operations remained ongoing, he said at the news conference.

"We're going to continue to search this pile until we are sure that there's no other survivors," Downey said then.

Miami-Dade Police Director Juan Perez said on Twitter late Thursday "Thank you first responders who assisted in the rescue efforts at the collapsed crossing bridge. Your efforts were valiant despite the final outcome."

He said that police "will now begin the recovery of victims and investigation. We will get to the truth for the sake of the family."

Miami-Dade Fire Rescue Division Chief Paul Estopinan had earlier said emergency workers found eight vehicles trapped under the bridge.

"We could only see eight [vehicles] from the exterior of the bridge," Estopinan said, adding that he did not know how many total cars might be affected. "We are creating holes just so that we can physically see [if there are others]."