Nantes supporters sang songs in support of Emiliano Sala in the heart of the city after the aircraft carrying the footballer disappeared en route from France to Cardiff.
The 28-year-old centre-forward, who had just become Cardiff City's record signing, was due to join his new teammates to train on Tuesday, but Jersey air traffic control (ATC) lost contact with the plane on Monday evening.
Nantes called for supporters to join together at Place Royale on Tuesday evening, where yellow tulips and other tributes were laid.
Fans chanted Sala's name as they often did when the Argentinian scored for the club. He was one of the top goalscorers in Ligue 1 this season when he sealed his move to the Premier League, with 12 league goals to his name.
Twitter user @MatthieuGruaz told the Press Association: "It was a sad atmosphere," adding that "a lot of people were crying", and saying there was "a lot of applause for him (Sala)".
Cardiff fans also paid tribute to the player, leaving flowers and scarves outside the club's stadium.
Search and rescue operations were suspended overnight following sunset on Tuesday. Guernsey Police said search efforts would resume at sunrise but the chances of passenger survival were "slim".
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