Images of the buckled structure at the college in Miami were shared across social media on Thursday afternoon.
A Florida Highway Patrol official said there were several fatalities, but police have yet to confirm a number.
It was unclear how many people were still trapped in eight vehicles beneath the bridge, Miami officials said.
"This is going to be a long incident. We are going to have rescuers here through the night, if not longer," Miami-Dade Fire Chief Dave Downey said on Thursday.