The crash happened near Cresthaven, some nine miles (14 km) from Mar-a-Lago, President Donald Trump’s resort in the wealthy enclave of Palm Beach County, around 12:50 EST (17:50 GMT).
Images show a large crater in the middle of a multi-lane road, with fire and debris from the Learjet 60 aircraft scattered across it, but nobody on the ground was hurt.
The aircraft had departed from Austin, Texas, and was headed to the Bahamas, the Federal Aviation Administration (FAA) said in a statement.
Flight analysis indicates that the jet was plummeting hundreds of feet per second before crashing.
In air traffic control audio recorded moments before the crash, someone in the cockpit can be heard reporting “moderate turbulence” and that the crew was “managing the ice”.
The person can then be heard saying the plane was “picking up precipitation” and “we need to climb”. Moments later, the same voice said the plane was descending at a rate of 10,000ft (3,048m) per minute.
The crew member declared an emergency, yelling “we are in an overspeed condition descending 20,000ft per minute”, before saying, “we are going to crash into the ground”.
Unverified footage posted on social media shows what appears to be a dash-camera recording of the moment of the crash. It shows vehicles driving on a residential suburban street, when suddenly an aircraft nosedives into the ground almost vertically, and explodes into a large fireball.
“When you see that video, it’s a jarring thing,” Florida Governor Ron DeSantis told reporters at a news conference after the crash. “It’s like a missile coming down, and a massive explosion, debris going everywhere.”
It is not yet clear who was aboard the jet when it crashed. DeSantis said “as of now, we don’t have any reports of anyone who was on the ground…who was killed or injured”.
Transportation Secretary Sean Duffy described the crash as a “horrific tragedy”, and said the FAA was sending a team to the scene to help an investigation by the National Transportation Safety Board.
“Please join me in praying for the families and loved ones of those we lost,” Duffy added.
Palm Beach County Fire Rescue has declared a “mass casualty incident”.
The Palm Beach County Sheriff’s Office said the crash happened on Military Trail, a six-lane road that features businesses and restaurants.
At a news conference, DeSantis and local officials said that 600 local residents were being evacuated from a nearby trailer-park community.
The impact of the crash caused considerable damage to local infrastructure, including its water lines, they said, and it would be at least 30 days before the road re-opened.
Thunderstorms had been reported in the area at the time of the crash, and it was heavily raining as the news conference was held.
Trump had been at Mar-a-Lago on Sunday morning, and departed from an airport nearby on Air Force One about an hour before the crash.