(CNN) Basketball legend Kobe Bryant and one of his daughters were among nine people killed Sunday morning when a helicopter crashed into a hillside in Calabasas, California, sources and officials said.

Bryant, 41, and his 13-year-old daughter Gianna Maria Onore Bryant had been expected at the Mamba Sports Academy in Thousand Oaks for a basketball game scheduled for Sunday. Gianna was expected to play in the game and Bryant was expected to coach, according to Lady Mavericks team director Evelyn Morales.

The helicopter crash, about 30 miles northwest of downtown Los Angeles, caused a brush fire, Los Angeles County Fire Department Chief Daryl Osby said. The crash killed all nine people aboard, Los Angeles County Sheriff's Department said

Earlier, the sheriff's department said five people were killed in the crash. Officials have not identified the victims.

Tony Altobelli told CNN his brother, Orange Coast College baseball coach John Altobelli , 56; John's daughter Alyssa and wife Keri were killed in the crash. Altobelli was a former assistant baseball coach at the University of Houston , the school said.

Alyssa and Gianna were teammates, Tony Altobelli said.

Orange Coast College baseball coach John Altobelli

Christina Mauser, an assistant girls basketball coach at Harbor Day School in Corona del Mar, California, was killed in the crash, her husband Matt Mauser, wrote on his Facebook page.

"My kids and I are devastated. We lost our beautiful wife and mom today in a helicopter crash," he wrote.

LA County Fire Department Capt. Tony Imbrenda said he didn't immediately have any information about whether the Sikorsky S-76B helicopter radioed a distress signal.

"Individuals that saw the aircraft said it was coming down at a fairly significant rate of speed and impacted the ground on the hillside," he told reporters.

Imbrenda said he didn't know where the helicopter took off from or where it was headed.

The helicopter was built in 1991, according to the Federal Aviation Administration. It was registered to Island Express Holding Corp, according to a FAA registry database.

Calls to Island Express were not answered Sunday. The company is based in Fillmore, according to the California Secretary of State database.

The FAA and National Transportation Safety Board are investigating the crash, the FAA said in a tweet. An NTSB team is expected to arrive in Calabasas on Sunday evening, the NTSB said in a tweet . The FBI said it is assisting the NTSB in the investigation.

The helicopter crashed on a hillside in Calabasas, California.

There was extremely low visibility at the time of the crash and conditions were foggy and cloudy with a drizzle, according to CNN Meteorologist Michael Guy. Pictures taken shortly after the crash showed fog in the area. The relative humidity was 100%, meaning the air was like soup, Guy said.

Due to the foggy conditions, the Los Angeles Police Department grounded its helicopters Sunday morning, a spokesman told CNN. Police spokesman Josh Rubenstein said the weather conditions did not meet the minimum standards for flying.

A heralded career

Bryant leaves behind his wife, Vanessa, and three daughters. His oldest daughter turned 17 a week ago; his youngest daughter is 7 months old.

Bryant's death comes a day after LeBron James passed him as No. 3 on the NBA all-time scoring list when he reached 33,643 points.

"Continuing to move the game forward @KingJames. Much respect my brother," Bryant tweeted Saturday night.

Born in Philadelphia, Bryant started playing basketball when he was 3 and went on to become one of the NBA's greatest champions. He was drafted straight out of Lower Merion High School near Philadelphia in 1996. He was the youngest player in NBA history at that time, at 18 years, 2 months and 11 days.

Bryant played his entire professional career with the Los Angeles Lakers and won five NBA championships. He has two Olympic gold medals for men's basketball.

Bryant retired in April 2016 after scoring 60 points in his final game. He said his "body knew it was time to say goodbye."

"In many ways he was the Los Angeles Lakers. When you think of Kobe Bryant, it's sports, but it's more than sports. He was part of our culture, Olympic teams, Hollywood, the father of four daughters," CNN sports analyst Christine Brennan said. Bryant was seen at women's sporting events including the US women's soccer team and WNBA games with his daughters, and he was "all about the empowerment of young women," she said.

Brennan said Bryant had "become a cultural icon and not just about sports, but about our culture and a huge piece of Americana and that's why this news is absolutely tragic."

Sportscaster Bob Costas told CNN Bryant was "always a legendarily hard worker."

"Even at the peak of his career before age and injuries may have slowed him a little bit, he always came back after each off season having added something to his game -- a new move, a new dimension," Costas told CNN.

Mourning Kobe

Everyone from current and former NBA players to former President Barack Obama mourned Bryant's death.

NBA clippers coach Doc Rivers, who has known Bryant for many years, was emotional when discussing his death. "He means a lot to me, obviously. He was such a great opponent. ... It's what you want in sports," Rivers said.

Rivers said Bryant "had that DNA that very few athletes can ever have. The Tiger Woods and Michael Jordans."

Most people will remember Kobe as the magnificent athlete who inspired a whole generation of basketball players. But I will always remember him as a man who was much more than an athlete. pic.twitter.com/9EZuwk8wrV — Kareem Abdul-Jabbar (@kaj33) January 26, 2020

Former Los Angeles Laker great Kareem Abdul-Jabbar, who has known Bryant since he was a boy, said Bryant was an athlete and leader who inspired generations of young athletes.

"He was one of the first ones to leave high school and come to the NBA and do so well, dominating the game and becoming one of the best scorers that the Los Angeles Lakers has ever seen," Abdul-Jabbar said in a video posted online.

"Rest in peace, young man, Abdul-Jabbar said. "This loss, it's just hard to comprehend."

The Hawks and @washwizards took 8 second and 24 second violations to honor Kobe Bryant. pic.twitter.com/ty7rZgyjFn — Atlanta Hawks (@ATLHawks) January 26, 2020

On the court Sunday, the Atlanta Hawks held a moment of silence as a tribute to Bryant before their game against the Washington Wizards. Following the moment of silence, Hawks guard Trae Young started the game wearing a No. 8 jersey to honor Bryant, then switched back to his No. 11.

On the opening possession, the Hawks took an 8-second backcourt violation and the Wizards followed by taking a 24-second shot clock violation.

Bryant wore both No. 8 and No. 24 in his NBA career.

Nooooooooooo God please No! — DWade (@DwyaneWade) January 26, 2020

When he learned of Bryant's death, retired NBA player Dwyane Wade tweeted: "Nooooooooooo God please No!"

I'm stunned. Words can't even come close to describing it. Just an incredibly sad and tragic day. — Scottie Pippen (@ScottiePippen) January 26, 2020

Former NBA player Scottie Pippen tweeted: "I'm stunned. Words can't even come close to describing it. Just an incredibly sad and tragic day."

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 pic.twitter.com/pigHywq3c1 — SHAQ (@SHAQ) January 26, 2020

NBA icon Shaquille O'Neal tweeted: "There's no words to express the pain Im going through with this tragedy of loosing my neice Gigi & my brother..."

Kobe was a legend on the court and just getting started in what would have been just as meaningful a second act. To lose Gianna is even more heartbreaking to us as parents. Michelle and I send love and prayers to Vanessa and the entire Bryant family on an unthinkable day. — Barack Obama (@BarackObama) January 26, 2020

"Kobe was a legend on the court and just getting started in what would have been just as meaningful a second act. To lose Gianna is even more heartbreaking to us as parents," Obama tweeted.

Los Angeles Mayor Eric Garcetti called Bryant 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.

"He will live forever in the heart of Los Angeles, and will be remembered through the ages as one of our greatest heroes."

President Donald Trump tweeted about Bryant's death, saying, "He loved his family so much, and had such strong passion for the future. The loss of his beautiful daughter, Gianna, makes this moment even more devastating...."

Across from the Staples Center in Los Angeles -- where the Grammy Awards were being held -- hundreds of fans stood around a memorial of Bryant's jerseys, photos and candles. Many wore Bryant's jerseys. Pumping their fists, some yelled, "MVP." They chanted "Kobe," and "GiGi," for his daughter.

A love of helicopters

Ten years ago, GQ Magazine wrote about how Bryant regularly took his own helicopter to work:

"He takes a private helicopter from Orange County, where he lives with his wife and two children, to every home game. It's a nice dash of glitz, a touch of showbiz (but) Bryant says the helicopter is just another tool for maintaining his body. It's no different than his weights or his whirlpool tubs or his custom-made Nikes.

"Given his broken finger, his fragile knees, his sore back and achy feet, not to mention his chronic agita, Bryant can't sit in a car for two hours. The helicopter, therefore, ensures that he gets to Staples Center feeling fresh, that his body is warm and loose and fluid as mercury when he steps onto the court."

The chopper was adorned with his logo.

This is a developing story.