Los Angeles Lakers great Kobe Bryant, 41, and his 13-year-old daughter were among nine people killed when a helicopter crashed in foggy conditions Sunday and then caught fire on a hillside in the Calabasas area outside Los Angeles.

Bryant's daughter, Gianna, and a teammate on her basketball team also were on board the helicopter when it went down northwest of LA, a city official said.

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The cause of the crash was unknown, but conditions at the time were such that the Los Angeles Police Department and the county sheriff's department grounded their helicopters.

The Los Angeles County medical examiner, Dr. Jonathan Lucas, said the rugged terrain complicated efforts to recover the remains. He estimated it would take at least a couple of days to complete that task before identifications can be made.

Bryant’s helicopter left Santa Ana in Orange County, south of Los Angeles, shortly after 9 a.m. and circled for a time just east of Interstate 5, near Glendale. Air traffic controllers noted poor visibility around Burbank, just to the north, and Van Nuys, to the northwest.

After holding up the helicopter for other aircraft, they cleared the Sikorsky S-76 to proceed north along Interstate 5 through Burbank before turning west to follow U.S Route 101, the Ventura Highway.

Shortly after 9:40 a.m., the helicopter turned again, toward the southeast, and climbed to more than 2000 feet (609 meters). It then descended and crashed into the hillside at about 1400 feet (426 meters), according to data from Flightradar24.

When it struck the ground, the helicopter was flying at about 160 knots (184 mph) and descending at a rate of more than 4000 feet per minute, the data showed.

The chopper went down in Calabasas, about 30 miles (48 kilometers) northwest of downtown Los Angeles. Bryant's Mamba Sports Academy in nearby Thousand Oaks was holding a basketball tournament on Sunday.

Federal transportation safety investigators were on their way to the scene. Among other things, they will look at the pilot's history, the chopper's maintenance records and the records of its owner and operator, said NTSB board member Jennifer Homendy at a news conference.

Kurt Deetz, a pilot who used to fly Bryant in the chopper, said the crash was more likely caused by bad weather than engine or mechanical issues.

"The likelihood of a catastrophic twin engine failure on that aircraft — it just doesn’t happen," he told the Los Angeles Times.

Kobe Bryant died in a helicopter crash on Sunday. The Los Angeles Lakers star played 20 years in the NBA, inspiring athletes everywhere.

Orange Coast College head baseball coach John Altobelli also was among the victims, the school says. He had coached at the Costa Mesa college for more than two decades. In a statement from the University of Houston, where Altobelli played baseball, officials said his wife Keri and daughter Alyssa also were killed in the crash.

Costa Mesa Mayor Katrina Foley tweeted that the dead also included Christina Mauser, a girls basketball coach at a nearby private elementary school. Her husband, Matt Mauser, founded the Tijuana Dogs, a popular Orange County band. In a Facebook post he said: "My kids and I are devastated. We lost our beautiful wife and mom today in a helicopter crash."

I just learned that our amazing Matt Mauser of TiajuanaDogs lost his wife Christina in the crash. She coached the girls team. This devastating tragedy gets worse by the hour. So much pain for so many local families. Our hearts are broken & grieving for the families impacted. — Mayor Katrina Foley (@KatrinaFoley) January 27, 2020

Daughter and mother Payton and Sarah Chester were also killed in the crash, according to Payton's grandmother Catherine George.

Said George, "Payton was 13-years-old. She loved playing for Kobe Bryant. He was a great coach. Her mother and father were very helpful… and they practiced a lot and for 13, she was very good."

George said the daughter and mother normally drove but took the helicopter out of convenience. She called the crash "a freak accident."

"Sarah was very involved with their children," George said about her daughter. "She was a great mom and did a lot of driving for the kids who all played sports. They go to St. Margaret’s. Payton has twin brothers."

The sheriff's department did not identify the victims.

Tearful and stunned fans gathered at the crash site, Bryant's training center in Newbury Park and Staples Center, where Bryant wowed crowds for 20 seasons, to mourn the five-time NBA champion and the Lakers' all-time leading scorer.

"Los Angeles will never be the same," a fan told NBC4. "Los Angeles will never forget this day."

Former teammates and other Laker greats shared their grief as they heard of Bryant's death.

"As I try to write this post, my mind is racing," Magic Johnson tweeted. "I’m in disbelief and have been crying all morning over this devastating news that Kobe and his young daughter, Gigi have passed away in a helicopter crash. Cookie and I are heartbroken."

From No. 8 to No. 24: Kobe Bryant’s Incredible Career

Witness Colin Storm was in his living room in Calabasas when he heard "what sounded like a low-flying airplane or helicopter."

"It was very foggy so we couldn't see anything," he said. "But then we heard some sputtering, and then a boom."

A short time later the fog cleared a bit and Storm could see smoke rising from the hillside in front of his home.

Bryant lived south of Los Angeles in Orange County for much of his adult life, and he often used helicopters to save time and avoid Southern California's notorious traffic. Even as a player, he often traveled to practices and games by helicopter, and he kept up the practice after retirement as he attended to his business ventures.

The Lakers team plane arrived back in Los Angeles from Philadelphia hours later. Players could be seen embracing, some appearing to wipe tears from their eyes.

Fans gathered outside Staples Center Sunday Jan. 27, 2020 to remember Kobe Bryant

NBA Commissioner Adam Silver called Bryant one of the most extraordinary players in NBA history.

"The NBA family is devastated by the tragic passing of Kobe Bryant and his daughter, Gianna," said NBA Commissioner Adam Silver. "For 20 seasons, Kobe showed us what is possible when remarkable talent blends with an absolute devotion to winning."

NBA legend Michael Jordan recognized Bryant for his talent and skill, but also praised his competitive streak, calling him one of the game's greats.

"I loved Kobe - he was like a little brother to me," Jordan said.

Bryant married wife Vanessa in 2001. The couple had four children.

The two met when Bryant was 21 years old and she was 17, and they were married six months later. Their relationship was rocky at times — Vanessa announced she was filing for divorce in 2011, and they reconciled in 2013. The couple had four children, including an infant born in June 2019.

Bryant, 41, retired in 2016 from the NBA after 20 seasons with the Lakers. He finished his legendary career third on the NBA's all-time scoring list.

"Kobe Bryant was a giant who inspired, amazed, and thrilled people everywhere with his incomparable skill on the court - and awed us with his intellect and humility as a father, husband, creative genius, and ambassador for the game he loved," Los Angeles Mayor Eric Garcetti said in a statement.

Bryant was born in Philadelphia. He was drafted out of high school by the Charlotte Hornets as the 13th overall pick in 1996. He was then traded to the Lakers and was voted an All-Star game starter at 19 in 1998.

Missing Attachment Former Los Angeles Laker Kobe Bryant was among those killed in a helicopter crash in Calabasas, California, Sunday morning near Los Angeles.

He played his entire 20-year career with the Lakers, winning the league’s Most Valuable Player award in 2008, making the all-star team 18 times and winning five NBA Championships.

He won three titles in a row alongside center Shaquille O'Neal.

O'Neal tweeted, "There's no words to express the pain Im going through with this tragedy of loosing my neice Gigi & my brother @kobebryant. I love u and u will be missed. My condolences goes out to the Bryant family and the families of the other passengers on board. IM SICK RIGHT NOW"

Bryant retired in 2016 as the third-leading scorer in NBA history, finishing two decades with the Lakers as a prolific shot-maker with a sublime all-around game and a relentless competitive ethic. He held that spot in the league scoring ranks until Saturday night, when the Lakers’ LeBron James passed him for third place during a game in Philadelphia, Bryant’s hometown.

He was the league MVP in 2008 and a two-time NBA scoring champion, and he earned 12 selections to the NBA’s All-Defensive teams. He teamed with Shaquille O’Neal in a combustible partnership to lead the Lakers to consecutive NBA titles in 2000, 2001 and 2002.

His Lakers tenure was marred by scandal when in 2003, Bryant was accused of raping a 19-year-old employee at a Colorado resort. He said the two had consensual sex, and prosecutors later dropped the felony sexual assault charge at the request of the accuser. The woman later filed a civil suit against Bryant that was settled out of court.

Bryant went on to win two more titles in 2009 and 2010, and retired in 2016.

#Update Downed aircraft is a helicopter. Flames extinguished. #Malibu deputies at crash site looking for survivors, 4200 blk Las Virgenes Rd #Calabasas #LASD pic.twitter.com/eixLhGhLyE — LA County Sheriffs (@LASDHQ) January 26, 2020