Florida plane crash: Crew members were making these requests to air traffic control just before the accident

The US National Transportation Safety Board (NTSB) says it will investigate whether parts of the jet plane that crashed in Florida broke before it went down and exploded, killing all nine on board.

On Sunday, a Learjet 60 bound for the Bahamas from Austin, Texas, crashed on a road nine miles (14 kilometers) from President Donald Trump's Mar-a-Lago resort.

The dead included a tech entrepreneur and his young family, as well as the 20-year-old co-pilot.

The NTSB said Monday that it will also investigate the extent to which ice and turbulence may have been a factor.

It was confirmed that after the jet took off from Austin, the crew informed air traffic control that they were encountering ice and mid-level turbulence.

The crew said, "We are facing rain clouds. We want permission to go up to a height of 37,000 feet."

NTSB member Tom Chapman said that less than 30 seconds later, the plane began descending and the crew issued a call for emergency assistance.

He told that after this the transmission was disrupted and he said- "Sadly, everyone on board the plane died."

The NTSB said ice and turbulence were factors in the crash, but determining the probable cause would be a lengthy investigative process.

At that time there was news of a storm in the area.

Officials are also trying to find out whether the cockpit voice recorder was present in the plane at the time of the crash and whether it can be recovered.

As part of this investigation, the NTSB is working closely with the Federal Aviation Administration (FAA), representatives from Learjet, as well as meteorologists and air traffic control experts.

Timothy Monville, an air safety investigator for the safety board, said removing the debris from the crater would be an "extremely challenging task."

Flight analysis shows that the jet was descending at hundreds of feet per second before it crashed.

In the air traffic control audio recording, a crew member can be heard declaring an emergency, shouting, "We are in overspeed and descending at 20,000 feet per minute", and then saying, "We are about to hit the ground."

About 35 seconds after the initial emergency declaration, the final comment from the cockpit is - "We're out of time."

The seven people who died and were traveling as passengers were identified in a joint statement issued by their families as tech entrepreneur Adam Robinson, his wife Helen Sharp and their two children - Emma and Charlie - as well as Rachel Reed, Charmy Fehr and Anita Maria Cetina.

In media reports, the pilot's name has been mentioned as Jeffrey Gregory, while Nathalia Filgueiras, who obtained her pilot's license at the age of 17, has been mentioned as the co-pilot.

In addition to the dead, a person on the ground suffered a leg injury when the plane crashed into the road.

The Palm Beach County Sheriff's Office said the crash happened on Military Trail, a six-lane road surrounded by businesses and restaurants.

Photographs from the crash site show a large, burning crater in the middle of a residential suburban road.

Debris was scattered over area playgrounds, businesses and homes, officials said at a news conference on Monday, possible evidence that the plane broke up before hitting the ground.

Unconfirmed footage posted on social media shows a dash-camera recording of the moment of the accident.

Trump was at Mar-a-Lago Sunday morning and had departed on Air Force One from a nearby airport about an hour before the crash.