Groups of youths in Stockholm have burnt down a restaurant and torched more than 30 cars in a fourth night of rioting.
The unrest is being blamed on police shooting and killing a 69-year-old knife-wielding man on May 13.
Hundreds of young people are said to have been involved in the rioting in immigrant suburbs of the Swedish capital.
Local media also said a police station office was set on fire in the suburb of Rågsved and police in the southern city of Malmo said two cars had been set ablaze.
Three police in Stockholm were also injured in the unrest.
The rioters have been heading out at nightfall over the past four days, ignoring calls from Sweden's prime minister to end the violence.
Selcuk Ceken, who works at a youth centre in one of the affected suburbs, said: "It's difficult to say why they're doing this.
"Maybe it's anger at the law and order forces, maybe it's anger at their own personal situation, such as unemployment or having nowhere to live."
The killing of a 69-year-old man in the suburb of Husby - which prompted accusations of police brutality - is said to have sparked the violence.
Sweden traditionally prides itself on having a reputation for social justice and hospitality towards refugees.
But a steady decline in welfare provision since the 1990s has been blamed for increased inequality and high unemployment, particularly among asylum seekers and immigrants.
Sweden ranks second in the absolute number of asylum seekers relative to its population, according to UN figures.
The left-leaning tabloid newspaper Aftonbladet labelled the riots a "gigantic failure" of government policies, which it said had led to inner city ghettos.