Amazon plane overruns runway and bursts into flames at Miami Airport

At least five people have died after an Amazon cargo plane barrelled off a runway at Miami International Airport, striking multiple vehicles and bursting into flames, a sheriff has confirmed.

The crash sent thick black smoke billowing into the sky and forced the closure of all runways at one of the United States's busiest airports.

More than 60 Miami-Dade Fire Rescue units responded to the crash, arriving to find the aircraft on fire as crews worked to extinguish the flames and assess patients.

The Federal Aviation Administration said the aircraft overran the runway about 2pm on Sunday, local time, after arriving from San Juan, Puerto Rico. Miami-Dade Fire Rescue officials said the plane struck multiple vehicles after leaving the runway.

Transportation Secretary Sean Duffy said the FAA was sending investigators and had issued a full ground stop at Miami International as emergency crews responded.

"At approximately 2pm today, Prime Air flight 7598 overran Miami International Airport's diagonal runway and is disabled at the north-west end of the airport," the airport said in a statement.

"All runways and taxiways at [Miami International Airport] are currently closed as of 3pm and a ground stop is in effect."

The Prime Air plane came to rest beside a roadway near two semi-trucks, according to images from the scene. The aircraft appeared to be resting on its belly and was largely intact despite the fire.

The flight had been operated by 21 Air, a cargo carrier based in North Carolina.

The 32-year-old Boeing 767 was originally built to carry passengers and flew for several airlines for more than two decades before being converted to a cargo plane in 2015, according to flight-tracking site Flightradar24

All runways and taxiways were closed, an airport spokesperson said. About 250 flights were delayed at the airport as of late Sunday afternoon, according to FlightAware, a website that tracks flight disruptions.

The FAA warned that delays were likely to persist even after the airport reopened, with arrivals and departures expected to resume at a reduced rate.

The National Transportation Safety Board said it was "gathering information".

"We're working closely with local authorities and officials to understand exactly what happened," Amazon spokesperson Kelly Nantel said in a social media post.

"Right now, our absolute priority is the safety, well-being, and care of everyone involved."