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 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.
'What has he been smoking?'
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?"
The hashtag #lastnightinSweden was soon trending on Twitter, and the Swedish embassy in Washington asked the state department for clarification.
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!"
What is Sweden's refugee policy?
Sweden, with a population of about 9.5 million, saw a sharp increase in asylum seekers in 2015, with more than 162,000 people claiming asylum. Almost a third came from Syria.
With the influx, tensions also rose with some isolated attacks on immigrants, as well as pro- and anti-migrant demonstrations.
Sweden had been offering permanent residence to all Syrians but the high number of arrivals prompted a change in the rules.
The number of asylum applications dropped to 29,000 in 2016 after Sweden introduced new border checks incurring longer processing times, as well as financial incentives for migrants who voluntarily returned to their country of origin.
The killing of a 22-year-old woman in January 2016 by an asylum seeker based at the centre where she worked put further pressure on the government to reassess its approach.
How safe is Sweden?
Sweden has generally low crime rates.
Preliminary statistics from the Swedish Crime Survey (in Swedish) show only a marginal increase in 2016 from the year before. Fraud and crimes against individuals were up, but drugs crimes and theft had decreased.
The number of reported rapes increased by 13%, although that is still lower than the number reported in 2014 (6,700), as Sweden's The Local reports.
What about terror attacks?
There have been no terror attacks in Sweden since the country's open-door policy on migration began in 2013.
In 2010, two bombs detonated in central Stockholm, killing the attacker - an Iraq-born Swedish man - and injuring two others, in what police described as a terrorist attack.
In October 2015, a masked man who was believed to have far-right sympathies killed a teacher and pupil in a sword attack.
And in Malmo last October, a fire at a Muslim community centre was claimed by the Islamic State group - the incident was cited by the White House in the list of incidents it deemed "under-reported" by the media.
Separately, Sweden is believed to have the highest number of Islamic State fighters per capita in Europe. About 140 of the 300 who went to Syria and Iraq have since returned, leaving the authorities to grapple with how best to reintegrate them into society.