Witnesses reported hearing around 12 to 15 shots fired in Drottninggatan, near Malmö.
Police said there was no indication of terrorism.
The man reportedly fired an automatic weapon at the crowd, who were celebrating Sweden's 1-0 victory against Korea, this evening. The statement said officers had information that "one person had been taken to hospital in a private vehicle".
Police were questioning witnesses after sealing off the area where the shooting took place.More news: Apple fined $9m for misleading customers
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Feuds between criminal gangs fighting over territory have become more common in major Swedish cities in recent years.
Swedish police said the motive for the attack is not yet known.
There were no immediate details on the conditions of the injured men.
Malmo is Sweden's third largest city and has a population of 340,000.