Groups of youths smashed shop windows, set cars ablaze, and burned down a cultural center last night as the riots that started in a Stockholm suburb after a fatal police shooting spread to other low-income areas of the Swedish capital. A police spokeswoman says 30 vehicles were set ablaze in six suburbs mainly populated by immigrants. Gangs of up to 60 youths also set fire to a school and a nursery and hurled rocks at police and firefighters. The unrest began over the weekend in response to the police shooting of a 69-year-old, knife-wielding man in a northwestern suburb. (More Stockholm stories.)