After a shocking Champions League defeat in Barcelona, Paris St. Germain players were confronted by hostile supporters on their return to the French capital.
Angry fans threatened PSG's players and families in what the club described as an "extremely hostile and aggressive climate" at Bourget Airport, north of Paris.
The French champions had suffered a 6-5 aggregate loss in Europe's premier cup competition Wednesday, with Barcelona overturning the biggest deficit in Champions League history to progress to the quarterfinals.
PSG won the first leg 4-0 and Unai Emery's team were favorites to reach the last eight.
But Barcelona struck three times after the 88th minute in the second leg at Camp Nou to complete an incredible comeback, sparking incredulous reaction from around the world.
Despite an increase in security, PSG said their players were threatened by "several individuals" at the airport.
The club claimed one individual had been hit by a car as the driver tried to escape a crowd that the club said was "physically threatening the players and their families."
PSG said a police investigation was under way.
"The club, and all those present, have informed the investigators of their readiness to help the investigation, to get to the bottom of this regrettable incident," read a club statement.
"The club strongly condemns the actions and behavior of the individuals in question."