A Northern Irish soccer fan died in the French city of Nice after scaling a sea-front railing and falling on his head onto a stone beach, officials said on Monday.
He was the first supporter to die during the Euro 2016 soccer tournament, which has been marred by off-pitch violence between fans since Friday's opening.
Nice's public prosecutor, Jean-Michel Pretre, said he had opened an investigation and it was not yet known what led to the 24-year-old's death, which involved a fall of seven or eight metres (around 25 feet).
"We're keeping all options open and have no favoured theory for now," Pretre said.
The incident took place at one end of Nice's beachfront Promenade des Anglais, which spans a wide bay. A police spokesman said that no trouble had been reported in the area.
Making their first appearance at a major finals for 30 years, the Northern Irish team lost their opening match on Sunday 1-0 against Poland.
Euro: Milik powers Poland to win over Northern Ireland
Shell-shocked Ukraine have no answers to German 'machine'
Why Super-sub Schweinsteiger 'can't play 90 minutes'
Turkey coach rues missed chance in Croatia defeat
Euro 2016: Points Table