Swedish police have launched an investigation after a riot erupted in a predominantly immigrant suburb of the capital, Stockholm.
One officer fired at rioters who threw rocks at police.
The unrest in the Rinkeby suburb on Monday night came after police tried to arrest a suspect on drugs charges.
It also comes after US President Donald Trump referred to Sweden in a speech on immigration problems, baffling Swedes about a non-existent incident.
Rioters, some of them wearing masks, threw rocks, set vehicles on fire and looted shops from about 20:00 (19:00 Irish Time/GMT) on Monday in Rinkeby, which has a history of unrest.
Warning shots were fired, but police later said one officer had also fired at least one shot at stone-throwers, a rare occurrence in Sweden.
No gunshot wounds were reported.
A number of other injuries were reported, including a shopkeeper.
A photographer from Dagens Nyheter said he was assaulted by a group of people when arriving to report on the unrest and spent the night in hospital.
The unrest subsided at about midnight.
Police spokesman Lars Bystrom said: "This kind of situation doesn't happen that often but it is always regrettable when it happens."
Sweden has seen urban unrest in some areas with large immigrant populations, where there have been job and integration issues.
At a rally in Florida on Saturday, Mr Trump suggested Sweden could face the kind of terrorist attacks that have hit France, Belgium and Germany.
He said: "You look at what's happening in Germany, you look at what's happening last night in Sweden. Sweden, who would believe this. Sweden. They took in large numbers. They're having problems like they never thought possible."
The statement about a particular incident on Friday night baffled Swedes, including former Prime Minister Carl Bildt, who tweeted: "Sweden? Terror attack? What has he been smoking?"
Mr Trump later tweeted that his statement "was in reference to a story that was broadcast on FoxNews concerning immigrants & Sweden".
Some people suggest Mr Trump might have been referring to a clip aired on Fox News on Friday night of a documentary about alleged violence committed by refugees in Sweden.
Mr Trump continued with a tweet on Monday, saying: "The FAKE NEWS media is trying to say that large-scale immigration in Sweden is working out just beautifully. NOT!"