Riots in the outskirts of the Swedish capital Stockholm have left vehicles and buildings in flames and destroyed two schools and a police station, reports say.
Several demonstrators were arrested, police were quoted as saying early on Friday.
Rioters have burned businesses, torched cars and attacked police and firefighters since the unrest broke out in areas with a high proportion of minorities on Sunday night, in a country widely considered successful in integrating its immigrants.
On Wednesday night, fire crews responded to about 80 fires around Stockholm, including about two dozen cars.
The trigger for the unrest has been cited as the police shooting on May 13 of a 69-year-old man in Husby, around 30km north of central Stockholm, where 80 per cent of the 12,000 inhabitants are immigrants and unemployment is high.
Many local residents see the shooting as an example of police brutality, and the violence has stirred debate in Sweden.
Police have refused to give the nationality of the victim of the shooting.
Prosecutors have launched an internal probe into the shooting.
Police say they shot the man in self-defence because he attacked them with a knife when they broke down the door to an apartment where he had locked himself up with a woman.
Fredrik Reinfeldt, prime minister, came under pressure during question time on Thursday, with critics linking the unrest to youth unemployment and immigration policy.
Surge in inequality
Sweden, known for its strong welfare state and egalitarian society, has had the biggest surge in inequality of any Organisation for Economic Co-operation and Development (OECD) country over the past 25 years, according to a recent publication by the global economic watchdog.
Commenting on the violence, Reinfeldt said: "This is not OK. We will not give in to violence.
"We must all help out to regain calm. The residents of Husby need to get their neighbourhood back."
Reinfeldt said Husby has been going in the right direction during his seven-year tenure, with employment increasing and crime falling.
Al Jazeera's Rory Challands, reporting from Husby, said that local authorities are doing their best to assimilate new immigrant arrivals.
"Husby is not some slum that the state has abandoned," he said.