Swedish police say a blast ripped through two adjacent apartment buildings in a southern city. It isn't immediately clear if there are casualties.

The explosion has blown out windows and destroyed balconies in the buildings in central Linkoping, about 175 kilometers (110 miles) southwest of Stockholm. One of the buildings had five stories, while the other had four floors.

Police said a bomb squad had been deployed to the area after Friday's blast, which occurred shortly after 0700 GMT (3 a.m. EDT).

The cause of the blast wasn't immediately known.