In a tweet, the club said:
Everyone at Arsenal is devastated by the shocking news that our former player Jose Antonio Reyes has died in a traffic collision in Spain.
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Reyes played for Arsenal between 2004-2007, joining the club halfway through their famous "Invincibles" season. It was reported last year that Reyes could return to the club as a coach, under Unai Emery, who had been his manager at Seville.
Former team-mate Thierry Henry tweeted that he was "devastated" to hear of Reyes' death, and called him a "superb team-mate and exceptional human being".
Spain and Arsenal team-mate Cesc Fabregas also posted an emotional tribute to Reyes, who he described as "My first great friend in a world of professional football, my roommate."
He added: "I will never forget when you and your family took me in your home on my first Christmas in England when I was alone and 16 years old."
Former manager Arsene Wenger also responded to the tragic news.
Freddie Ljungberg who also played with Reyes said he was "numbed by the news."
BBC Sport pundit Gary Lineker commented "How terribly sad. RIP."
Journalist and Arsenal fan Piers Morgan tweeted: "The invincibles, one of the greatest teams in football history, with Jose Antonio Reyes among them."
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