( CNN ) -- Police in the Swedish capital , Stockholm , have called in reinforcements after the city 's suburbs were hit by a fifth night of riots . Gangs set fire to two schools and a police station in the city on Thursday , police spokesman Kjell Lindgren told CNN . About 30 cars were also torched , with the blaze from one vehicle spreading to a nearby shop . `` Police and firemen were also attacked again with rocks overnight , but no one was severely hurt , '' Lindgren said . `` The level of violence has decreased , '' he added , `` but the problem remains . '' Extra police have been called in to help officers deal with the riots and a number of other events , including football matches , planned to take place in the city over the weekend . Read more : Swedish suburbs shaken by violence . `` Our resources are very stretched , so we need additional officers to make sure we cope with all the events and this violence , '' Lindgren said . The riots broke out after days of rising tensions following the death of a 69-year-old man who was shot by police earlier this month while wielding a machete in the Stockholm suburb of Husby . However , police say they are not sure what sparked the outbreak of violence . The area is blighted by high unemployment and crime levels . A total of 29 people have so far been arrested in connection with the riots , Stockholm Police said in a statement on their website . Read more : Swedish capital sees 3 nights of riots . The city 's police chief pledged that more culprits would likely be arrested in the coming days . `` Initially we encountered a lot of violence , so our priority was to ensure the safety of the firemen , '' Mats Lofving said in a statement . `` Now we are gearing up our ambition to start arresting more people . `` We have a lot of filmed material that we will be studying closely . We hope to arrest more of those who may think that they have gotten away with it because the worst is over . '' Earlier this week , Swedish Prime Minister Fredrik Reinfeldt vowed to take a stand against the rioters . `` We have to show that we wo n't allow a group of young men who believe in the use of violence to run society , '' Reinfeldt said .
Swedish capital , Stockholm , rocked by a fifth night of riots . Two schools and a police station attacked and set on fire , 30 cars torched . Police call in reinforcements from neighboring districts to help deal with violence . Tensions high since police shot dead a 69-year-old man armed with a machete .