At least five people were killed and five others injured when an Amazon cargo aircraft operated by 21 Air overran a runway while landing at Miami International Airport on Sunday, striking several vehicles and catching fire.

The Boeing 767-300, operating as Amazon Prime Air Flight 7598, came off the runway at about 2 pm local time after arriving from Luis Muñoz Marín International Airport in San Juan, Puerto Rico, according to the US Federal Aviation Administration (FAA).

The aircraft crossed the runway's usable area and continued onto the airport perimeter, where it struck multiple vehicles before coming to a stop and catching fire. Emergency crews reported heavy flames and thick black smoke from the aircraft.

Miami-Dade Fire Rescue Chief Raied “Ray” Jadallah said five people were killed and five others injured. Three of the injured were in critical condition and taken to a trauma centre, while two others were transported to hospitals.

Several victims were trapped in vehicles struck by the aircraft and had to be extricated by rescue crews. The pilots were also removed from the aircraft and taken for medical treatment.

More than 60 emergency units and about 200 personnel responded to the crash, according to authorities. Firefighters also dealt with a fuel leak at the scene.

The aircraft was travelling at nearly 130 mph when it left the usable portion of the runway, according to flight-tracking data cited by Reuters. The reason why the aircraft failed to stop remains unknown and will be determined by investigators.

The FAA confirmed that the aircraft was 21 Air Flight 7598. Amazon Air is Amazon's air-cargo network, but its flights are operated by partner airlines. Amazon's own website lists 21 Air among its direct air-carrier partners.

“We’re heartbroken to learn that five people lost their lives in today’s incident at Miami International Airport,” Amazon spokesperson Kelly Nantel said, expressing condolences to the victims' families and those affected by the crash. Amazon said it would cooperate fully with the investigation.

21 Air also expressed condolences to the victims' families and said it was cooperating with authorities.

The 32-year-old Boeing 767 had been converted from passenger service to a freighter and was operating a cargo service for Amazon. 

The crash temporarily brought operations at Miami International Airport to a halt, with numerous flights cancelled or delayed. Operations were gradually restored later in the day.

The National Transportation Safety Board (NTSB) is leading the investigation, with the FAA also investigating. Investigators are expected to examine the aircraft, runway conditions, weather, flight data, maintenance records and the circumstances surrounding the landing to determine why the aircraft was unable to stop.

The cause of the crash has not been established.