STOCKHOLM — A powerful explosion ripped through two adjacent apartment buildings in a southern Swedish city on Friday, slightly injuring 25 people, officials said. The cause of the blast wasn’t immediately known.

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

Police said a bomb squad had been deployed to the area as a precaution after the blast, which occurred shortly after 0700 GMT (3 a.m. EDT). The area was sealed off by police.

“As for now, we don’t have any information to believe this is terror-related,” police spokesman Bjorn Oberg told The Associated Press.