Monza soccer player Pablo Mari will undergo surgery on Friday after being stabbed along with five other people at a supermarket in a shopping mall near Milan, the hospital where he is being treated said.

Arsenal's Pablo Mari 

Italy's Carabinieri police said one person had died in Thursday's attack, a 47-year-old Bolivian national who worked at the supermarket in the town of Assago. Another employee was injured along with four customers, including Mari.

A 46-year-old suspect was detained but the motive was not clear, the Carabinieri said.

They said late on Thursday the suspect had mental health disorders and was under guard in a psychiatric ward.

View of the supermarket

Milan's Niguarda hospital said on Friday Mari was in a stable condition, having suffered non-deep stab wounds in his back. It said in a statement he had arrived at the hospital "alert and conscious" and was due to have an operation to suture the wounds.

A spokesman for his Serie A side confirmed he was due to have surgery but said he had no further details.

A police officer stands guard

Monza Chief Executive Adriano Galliani had said on Thursday Mari's life was not in danger and he should recover quickly, calling him a "warrior".

Mari, a 29-year-old Spanish centre back, is on loan at Monza from Premier League club Arsenal, which said in a statement on Thursday: "We have been in contact with Pablo's agent who has told us he's in hospital and is not seriously hurt."