A man grabbed a knife from a supermarket shelf Thursday and stabbed five people, killing one and wounding four others, including Spanish soccer player Pablo Mari, Italian authorities said. Police arrested a 46-year-old Italian man suspected in the attack at a shopping center in Assago, a suburb of Milan, carabinieri said. A supermarket employee died en route to the hospital, according to the news agency ANSA, which said three other victims were in serious condition. Another person was treated for shock but not hospitalized, police said.

The motive for the attacks was unknown, but police said the man showed signs of being psychologically unstable. There were no elements to suggest terrorism. Mari, who is on loan to the Serie A club Monza from Arsenal, was among the wounded. Arsenal said in a statement that Mari was at the hospital but was not seriously hurt. Monza club CEO Adrian Galliano wished the soccer player a speedy recovery in a message posted on Twitter.

Witnesses told ANSA they saw people fleeing the supermarket in shock, and as the gravity of the situation became clear, shop workers pulled down the store’s shutters. The Carrefour supermarket chain said that police and ambulance crews responded immediately to calls alerting them about the attack. The chain expressed its sympathies to employees and clients affected by the attack and said it was offering them psychological support. Arsenal have been in contact with Pablo’s agent who has told us he’s in hospital and is not seriously hurt.

The Gunners only needed a point in the Netherlands to advance to the last 16 next March. But Joey Veerman’s first-time finish from 16 yards and a header by substitute Luuk de Jong – after a mistake by keeper Aaron Ramsdale on his European debut – meant Arsenal lost in Europe for the first time this season. PSV, managed by former Manchester United forward Ruud van Nistelrooy, also had three goals ruled out for offside as Arsenal were well beaten.

The Gunners need to beat Zurich, who they defeated 2-1 in Switzerland on 8 September, in their final group game next Thursday at Emirates Stadium (20:00 GMT) to guarantee a place in the last 16. If they fail to win and PSV beat Bodo/Glimt in Norway, Arsenal will face two extra games in the knockout round playoffs, which will also include teams who finished third in their Champions League groups, including Barcelona. Arsenal had been pretty much faultless in Europe this season after four wins out of four, including a narrow 1-0 win over PSV at Emirates Stadium last week. This was their biggest test to date on the continent, yet they were second best as PSV – who included Jarrad Branthwaite, on loan from Everton, in the centre of defence – produced a dominant performance in front of their own fans.

Cody Gakpo and 19-year-old former Paris St-Germain midfielder Xavi Simons caused the Gunners defence all sorts of problems. Gakpo had two goals ruled out for offside and Simons one. Arsenal were living dangerously and it was no surprise when Veerman swept the hosts ahead before De Jong struck after Ramsdale failed to connect while trying to clear a corner. By the end, Arsenal finished with substitutes Gabriel Jesus, Bukayo Saka and Thomas Partey on the pitch but they were unable to rescue a point. They remain favourites to finish top of the group, but Arteta now seems unlikely to be in a position to rest key players before the heavyweight London derby at Chelsea on 6 November after a second defeat in 16 games this season.