A man has been arrested after an assistant referee was hit by an object thrown from the stands during St Etienne's 2-1 win over Lyon in Ligue 1 on Sunday.
Lyon were about to take a throw-in in the 44th minute when the official was shown holding a hand to his head after being hit by what appeared to be a coin, L'Equipe reported.
Lyon's medical team attended to the assistant referee before the players and officials left the pitch.
The game was interrupted for about 40 minutes.
"Based on information provided by the club and in collaboration with the authorities, the individual was arrested as he left the stadium and is now in police custody," hosts St Etienne said in a statement.
"Saint-Etienne will file a formal complaint against him tomorrow. The club will also act with the utmost severity, imposing its own strictest sanctions to ensure this isolated act does not go unpunished."