Kobe Bryant has reportedly died in a helicopter crash on Sunday morning in California .The NBA star, 41, was travelling with four people in his private helicopter when it crashed in Calabasas.

All five people onboard are reported to have died in the accident.

A call for a downed helicopter went out at 10.01am local time, according to the Los Angeles County Sheriff's Department. Firefighters arrived at the scene and put out the flames.

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However, it was later reported that there were no survivors from the crash.

"Unfortunately there were no survivors," said Tony Imbrenda of the Los Angeles County Fire. 

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Immediately messages started filtering in from across the internet, with hundreds offering prayers for Kobe's wife, Vanessa Bryant, who is not thought to have been on board.

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President Donald Trump wrote on Twitter: "Terrible news."

Meanwhile, fellow NBA legend Kevin Love tweeted, "Please no. Please god no. It can't be true."

Celebrity reporters at TMZ quoted eyewitnesses as saying they heard the helicopter's engine in trouble just before it went down.