In Rinkeby a predominantly immigrant district in northern Stockholm, firefighters rushed to put out flames that engulfed six cars parked alongside each other. Five cars were totally gutted, and one sustained more moderate damage, according to an AFP photographer on the scene.
The continued vandalism left local residents irate, with hundreds gathering at the scene to express their frustration.
"People are furious; they think Rinkeby is better than this," Scanpix photographer Fredrik Sandberg told the TT news agency from the scene.
Three more cars were torched in the southern suburb of Norsborg, and a police station in Älvsjö, also on the city's south side, was set on fire but quickly extinguished, police said.
Eight people were arrested in Älvsjö, while four arrests were made in Norsborg.
Firefighters also reported a school in Tensta, another north Stockholm suburb, was set ablaze but quickly extinguished, while a Montessori school in the neighbouring Kista suburb was also on fire.
"This makes me extra angry. Are things going to get better if people set schools on fire?" Kista resident Aleks Sakala, a father with two children enrolled at the school, told the Expressen newspaper.
"This is as far from good sense as you can get. This is madness. Where will my kids go to school tomorrow? They probably won't be able to finish out the term."
Meanwhile, police in Södertälje, a town south of Stockholm, said rioters threw stones at them as they responded to reports of cars set alight.
Car fires were reported in the suburb of Sollentuna, while a car fire in Jordbro had spread to a nearby shopping centre before being brought under control, police told the Aftonbladet newspaper.
"It still feels like things have been calmer tonight, at least that's our impression. There are a lot of volunteers out on night patrols and that may have helped," police spokeswoman Towe Hägg told the newspaper.
The previous night, the fire brigade had been called to some 90 different blazes, most of them caused by rioters.
The unrest that has plagued Stockholm throughout the week began Sunday in Husby, with many believing they were triggered by the fatal police shooting of a 69-year-old Husby resident last week after the man wielded a machete in public.
IN PICTURES: See the damage from the Husby fires
The man had fled to his apartment, where police have said they tried to mediate but ended up shooting him dead in what they claimed was self-defence.
Local activists said the shooting sparked anger among youths who claim to have suffered from police brutality. During the first night of rioting, they said police had called them "tramps, monkeys and negroes."
Police meanwhile have downplayed the scale of the events.
"Every injured person is a tragedy, every torched car is a failure for society... but Stockholm is not burning. Let's have a level-headed view of the situation," Ulf Johansson, deputy police chief for Stockholm county, said Thursday.