Arsenal defender Pablo Marí, currently on loan at Serie A club Monza, was one of at least five people stabbed at a shopping market in the Assago area of Milan, according to Adam Crafton of The Athletic.
He is not believed to have suffered serious injuries.
"I just found out," Arsenal manager Mikel Arteta told reporters on Thursday after his club's 2-0 loss to PSV Eindhoven in the Europa League. "I know [Arsenal technical director] Edu has been in touch with his relatives. He's in hospital but he seems to be OK."
This article will be updated soon to provide more information and analysis.