A man grabbed a knife from a Milan supermarket shelf on Thursday and stabbed five people, killing one and wounding four others, including Spanish footballer Pablo Mari.
Police arrested a 46-year-old Italian man suspected in the attack at a shopping centre in Assago, a suburb of Milan.
A supermarket employee died en route to the hospital, according to the news agency ANSA, which said three other victims were in serious condition.
The motive for the attacks was unknown, but police said the man showed signs of being psychologically unstable.
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.
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