A fourth night of unprecedented riots in Stockholm has seen unrest spread, with a restaurant and up to 40 cars burnt, police told the BBC.
Three police officers were hurt as rioters threw stones and directed laser pointers at emergency services.
The unrest began on Sunday in the deprived, largely immigrant suburb of Husby, to the north-west of the city.
Days earlier the police had shot dead an elderly man who had allegedly threatened to kill them with a machete.
The worst of the latest rioting has been in the south of the city.
Stockholm police spokesman Kjell Lindgren said the rioters were a "mixture of every kind of people".
Activists in the Husby area have accused police of racist behaviour - an accusation greeted with scepticism by the police themselves.
Prime Minister Fredrik Reinfeldt has said everybody must take responsibility for restoring calm in Stockholm.
"It's important to remember that burning your neighbour's car is not an example of freedom of speech, it's hooliganism," he said on Wednesday.
It is unclear how many cars have been burnt since Sunday as a result of the rioting, Mr Lindgren told the BBC.
But on Wednesday night 10 attacks were reported in the north-western suburbs while between 20 and 30 were burnt in southern parts of Stockholm.
Firefighters struggled to contain the fire at the restaurant in the southern suburb of Skogas, where young people pelted them with stones, the spokesman said.
Groups of rioters, as small as five people and as large as 100, have been seen this week, Mr Lindgren said.
They have typically waited for emergency services to attend a fire before attacking them.
Green laser pointers have also been shone in the eyes of the emergency services, according to Mr Lindgren.
No arrests were made on Wednesday night because the police's priority was to disperse mobs and ensure access to fires for the fire brigade, he said. Overall, five people have been arrested since Sunday.
'Very young people'
The Stockholm police spokesman said rioting had occurred in both deprived parts of the city and parts that would be considered "normal".
"My colleagues say the people on the streets are a mixture of every kind of people you can think of," he added.
"We have got Swedes, we have got very young people, we have got people aged 30 to 35. You can't define them as a group.
"We don't know why they are doing this. There is no answer to it."
In Husby, more than 80% of the 12,000 or so inhabitants are from an immigrant background, and most are from Turkey, the Middle East and Somalia.
Rami al-Khamisi, a law student and founder of the youth organisation Megafonen, told the Swedish edition of online newspaper The Local this week that he had been insulted racially by police. Teenagers, he said, had been called "monkeys", fuelling resentment.
The Stockholm police spokesman said he was aware that prosecutors were investigating complaints, and the behaviour of one police officer in particular.
But he added that he could "hardly believe" all the complaints being made were true.
"We have never had this kind of riots before in Stockholm, not this amount of riots and not this number of hot areas," said Mr Lindgren.