Federal investigators on Monday sifted through the wreckage of the helicopter crash near Los Angeles that killed basketball legend Kobe Bryant and eight other people, hoping to find clues to what caused the accident that stunned the world.

Bryant, 41, was traveling Sunday with his 13-year-old daughter Gianna and seven other passengers and crew when the Sikorsky S-76 slammed into a rugged hillside in thick fog in Calabasas, northwest of LA. There were no survivors.

A five-time NBA champion for his only team, the LA Lakers, and a double Olympic gold medalist, Bryant is widely regarded as one of the greatest basketballers in history.

He was traveling on his private helicopter from Orange County, where he lived, to his Mamba Sports Academy in Thousand Oaks.

The Federal Aviation Administration and the National Transportation Safety Board are leading the investigation into the crash.

Kurt Keetz, a pilot who said he flew Bryant from 2014 to 2016, told the Los Angeles Times he suspects the crash was most likely caused by bad weather rather than engine trouble.

"The likelihood of a catastrophic twin-engine failure on that aircraft – it just doesn't happen," he said.

The fog was heavy enough on Sunday that the Los Angeles Police Department grounded its helicopters until the afternoon, spokesman Josh Rubeinstein said.

The Los Angeles County Sheriff's Department also had no helicopters flying Sunday morning, Sheriff Alex Villanueva told reporters.

The Washington Post, citing air traffic control audio recordings, reported however that Bryant's pilot had received clearance to fly.

Witnesses told local media the helicopter appeared to be flying very low and seemed to struggle before it slammed into a hillside.

Dozens of firefighters and paramedics battled across hilly terrain to reach the flaming wreckage but found no survivors.

Logistical nightmare

Villanueva said the recovery effort would probably take days because the steep terrain at the crash site made it a "logistical nightmare."

Apart from Bryant and his daughter Gianna, the other passengers on the flight included baseball coach John Altobelli, his wife Keri and their daughter Alyssa, who played basketball at the same club as Gianna.

Christina Mauser, an assistant coach of the Mamba girls' basketball team, was also killed along with Sarah and Payton Chester, a mother and daughter.

News of the crash reverberated across the globe and hundreds gathered at the Staples Center in downtown Los Angeles, where Bryant wowed fans for 20 years, placing flowers, candles and messages for their fallen hero.

"He meant hard work... and he was just such a good person," said Anthony Jackson, 62, who carried a collage of photos of Bryant.

Tributes have also flooded in from former U.S. presidents, pop stars and athletes from different sports, a sign of how the man known as the "Black Mamba" had transcended basketball.

"Kobe was a legend on the court and just getting started in what would have been just as meaningful a second act," Barack Obama tweeted.

Bryant's career began in 1996, straight out of high school. On top of his NBA championship wins, he helped the U.S. squad of all stars to Olympic titles in 2008 in Beijing and 2012 in London.

Fairytale farewell

Bryant bowed out of the NBA in 2016, scoring 60 points in a fairytale farewell appearance at the Staples Center.

The son of former NBA player Joe "Jellybean" Bryant, the Lakers legend was born in Philadelphia while his father played for the 76ers.

The elder Bryant played from 1984 to 1991 in Italy, giving young Kobe a global worldview as he grew up dreaming of following his dad into the NBA.

He would eventually join the ranks of professionals at the age of 17, jumping directly into the NBA, only the sixth player to make such a leap.

At 18, Bryant became, at the time, the youngest player or starter in an NBA game and the youngest winner of the NBA Slam Dunk Contest.

With Bryant alongside Shaquille O'Neal, the Lakers captured three straight NBA crowns from 2000-2002, returning the team to glory days unseen since 1988.

After his playing career, Bryant branched out into the entertainment industry.

In 2018, he won an Oscar for his animated short film "Dear Basketball," a love letter to the sport which brought him fame and fortune.

Meanwhile, the NBA announced on Monday that the Lakers and the Clippers will not play as planned on Tuesday night, as the players and others throughout basketball grieve the death of Bryant, a star with the Lakers for two decades.

In a statement, the league said the game had been postponed to a later date, which was not immediately announced, "out of respect for the Lakers organization."

Eight other NBA games scheduled for Tuesday are expected to be played as planned.