Rioting has continued for a sixth consecutive night in Stockholm, but police reinforcements sent to the city reduced the violence.
Dozens of youths set cars and a recycling station ablaze in the Swedish capital on Friday night. Some other areas also had problems.
An empty building was set alight in Sodertalje, a town just out of Stockholm. In Orebro, police said 25 masked youths set fire to cars and a school and tried to do the same at a police station.
Police officers went earlier sent from Gothenburg and Malmo, which have both experienced riots in recent years.
Firefighters were dispatched to 70 different locations in greater Stockholm on Thursday night. That was calmer than the previous night, when 90 incidents were handled.
The riots began on Sunday in the north-western suburb of Husby, an immigrant area and the unrest has since spread around the city.
According to Swedish Radio, the If, Folksam and Trygg-Hansa insurance companies have each received 20 - 30 claims for cars that have been torched.
The BBC reports more than 80% of the 12,000 inhabitants in Husby have an immigrant background. Most are from Turkey, the Middle East and Somalia.
Foreign-born residents now comprise some 15% of the population of Sweden.
A recent government study showed that up to a third of young people aged 16 - 29 in some cities neither study nor have a job.
The gap between rich and poor in Sweden is growing faster than in any other major nation, according to the OECD.