Swedish police are probing an explosion in the city of Linkoping that shattered windows and damaged several buildings on Friday.
There were no immediate reports of serious injuries, but several ambulances have been dispatched to the scene on the outskirts of the city centre, local media reported.
Images showed damage to balconies as well as shattered windows.
Police said they have cordoned off several blocks around the scene, and the national bomb squad has been dispatched.
Linkoping, which has a population of about 150,000 people, is located about 175 kilometres South-West of the capital Stockholm.