Investigators say Florida jet may have broken apart midair as victims of crash that killed nine are named

Investigators examining the crash of a private jet in Florida say there is evidence the aircraft began breaking apart before it slammed into a multi-lane highway and exploded, killing all nine people on board.

The Learjet 60 was travelling from Austin, Texas to the Bahamas on Sunday when it nosedived into Military Trail, a six-lane road lined with businesses and restaurants in Palm Beach, at around 12:50 local time. Among the dead were a tech entrepreneur, his young family and a 20-year-old copilot.

The US National Transportation Safety Board (NTSB) said weather conditions would be a central focus of the investigation. Heavy rainfall and thunderstorms had been reported in the area at the time, and the impact carved a huge crater into the road, near the entrance to a mobile home park, which was partially filled with water from severe storms.

"The biggest obstacle that we're going to have is recovering the major wreckage from the impacted crater on the roadway," lead investigator Tim Monville told a news conference on Monday. Debris was scattered across sports fields, businesses and homes in the area.

"We do have some evidence that there was some breakup of the aircraft before impact," said the NTSB's Tom Chapman. "We may find parts of the aircraft some distance away from the actual impact site." Officials are also working to establish whether a cockpit voice recorder was on board and whether it can be retrieved.

Flight analysis indicates the jet was plummeting hundreds of feet per second before crashing. In air traffic control audio, someone in the cockpit reported "moderate turbulence" and said the crew was "managing the ice", before saying the plane was "picking up precipitation" and that "we need to climb". Moments later the same voice reported a descent rate of 10,000ft (3,048m) per minute.

An emergency was declared, and the crew could be heard yelling "we are in an overspeed condition descending 20,000ft per minute", followed by the words "we are going to crash into the ground". One man in a car on the ground suffered a leg injury.

The seven passengers were named in a joint family statement as tech entrepreneur Adam Robinson, his wife Helen Sharp, their children Emma, four, and Charlie, two, along with Rachael Reed, Charmi Fehr and Anita Maria Cetina. The pilot was named in media reports as Jeffery Gregory, and Nathalia Filgueiras, 20, who earned her pilot's licence at 17, was reported to be the copilot.

Robinson and Sharp's relatives described them as "devoted parents" whose children were "the light of their lives". "Helen and Adam were the love affair that will last forever. Their warmth, generosity and gift for making people feel welcome touched so many lives," the statement said. On his LinkedIn page, Robinson described himself as founder and CEO of RB2B and Retention.com and CEO of Moltsets; he previously worked at Lehman Brothers and Barclays. Sharp was an artist, according to media reports.

The statement said Cetina "cared for Emma and Charlie with tenderness and devotion, and she was truly part of the family", while Reed and Fehr were remembered as "full of joy and adventure". Filgueiras's mother, Camila Corteleti, confirmed her daughter's death to US media, telling the New York Times: "She loved the freedom. It was completely different seeing the world from the top." A spokesperson for East Coast Jets, where pilot Jeff Gregory once worked, said: "We are deeply saddened to learn that Capt Jeff Gregory was among those who lost their lives in yesterday's tragic aviation accident in Palm Beach."