Former world champion Jenson Button has led tributes to "real fighter" Jules Bianchi after the Frenchman died as a result of severe head injuries in a crash at the 2014 Japanese Grand Prix.
The 25-year-old had been in a coma since crashing his Marussia car into a recovery vehicle nine months ago.
McLaren driver Button tweeted on Saturday: "Last night we lost a truly great guy and a real fighter #RIPJules.
"My sincerest condolences to his family and friends."
Reigning champion Lewis Hamilton also tweeted: "A sad, sad day today, guys. Please pray for Jules' loved ones. RIP Jules. God bless."
The accident happened when Bianchi's car slid off the wet Suzuka track and into a crane picking up the Sauber of German driver Adrian Sutil, who had crashed at the same spot one lap earlier.
Bianchi was part of the Ferrari young driver programme.
Former team-mate Chilton remembers Bianchi
Ex-Marussia driver Max Chilton, 24, raced as team-mate to Bianchi for two years in F1. They also competed in karting from the age of 10 before rising through the racing ranks together.
The Briton tweeted: "No words can describe what his family & the sport have lost. All I can say is it was a pleasure knowing and racing you."
A 'shining talent' for Manor Marussia
Bianchi made his debut for Marussia in 2013 and a year later he scored both his and his team's first points in F1 after finishing ninth in Monaco.
John Booth, team principal for Manor Marussia, said in a statement on Saturday: "Jules was a shining talent. He was destined for great things in our sport; success he so richly deserved.
"He was also a magnificent human being, making a lasting impression on countless people all over the world. They recognised, as did we, that at the same time as being a fiercely motivated racer, he was also an extremely warm, humble and intensely likeable person, who lit up our garage and our lives."
'A world champion in the making'
F1 pundit Eddie Jordan told BBC Breakfast that Bianchi was developing into a world-class driver.
"Very seldom do we find a real jewel, like Lewis Hamilton, Ayrton Senna and Michael Schumacher. Jules had the potential to be in that league," said Jordan, a former team boss and BBC Sport expert.
"It was unfortunate circumstances. We have things to learn but the virtual safety car has improved things and it couldn't be safer now.
"Bianchi was so well respected, loved and adored. A smashing boy and a world champion in the making."
British former F1 driver and BBC commentator Allan McNish added: "He had a huge smile. It wasn't just about what he could do on the circuit, it was about what he did off it as well. He lifted that team.
"If you look back to Monaco 2014, it was one of his best drives and it gave Manor their first ever points in F1. It gave them hope to be able to continue and try and revive the team for 2015.
"It's not just about the loss of a friend and a colleague, it's about the loss of someone with such a huge talent. He was taken away far too young."
F1 group chief executive Bernie Ecclestone said: "It was so sad to hear the news about Jules. We are now going to miss a very talented driver and a really nice person. We must not let this ever happen again."
|BBC Sport chief F1 writer Andrew Benson|
|The Frenchman was one of the most promising of a new generation of Formula 1 drivers. In only 34 races he had done enough with the back-of-the-grid Marussia team to suggest he had a bright future in the sport.|
|Read Andrew's thoughts here.|
Social media reaction
McLaren's Fernando Alonso: "Friend, companion, talent, smile. Eternal. Rest in peace Jules. Always with us."
Mercedes driver Nico Rosberg: "Extremely sad to hear that Jules Bianchi passed away. Thinking about Jules and his family."
Former McLaren and Benetton driver Martin Brundle: "RIP Jules Bianchi. It was a pleasure and privilege to have known him in his all-too short life. Sad day, condolences to his family and friends."
Manor Marussia driver Roberto Merhi: "Very sad day for motorsport, the best driver that I raced against has left us after nine months fighting for his life. RIP my friend Jules."
Toro Rosso driver Max Verstappen: "Today we have lost an amazing talent and person. Words can't describe our feelings right now. We will all miss you Jules."
Red Bull team: "A tragic loss. All of our thoughts are with the family and friends of Jules Bianchi. #RIPJules #JB17."
Force India team: "Our thoughts are with Jules's family and friends in this moment. You will be sorely missed, Jules. Rest in Peace."
Toro Rosso driver Carlos Sainz: "Horrible news. Rest in peace mate. A great example of fight and courage for all of us. You will always be with us."
Former McLaren and Lotus driver Heikki Kovalainen: "RIP Jules Bianchi. My sincerest condolences to all of his family."