HELSINKI, Finland —

       A powerful explosion in an apartment building in the Swedish city of Gothenburg injured up to 20 people Tuesday, three of them seriously, and forced the evacuation of hundreds more, police and rescue workers said.

       Police spokesman Stefan Gustafsson told the Associated Press that eight people were taken to the hospital and that the cause of the explosion was not yet known.

       The explosion took place just before 5 a.m. in the Annedal district in central Gothenburg (also known as Goteborg), Sweden’s second-largest city. Fires spread to several apartments, and crews from the local fire department were still working to extinguish the flames at 9 a.m.

       “It was burning in several places in the property and in several apartments after the explosion,” said Jon Pile, operations manager at the local rescue service.

       Advertisement

       Building resident Lars Hulten told the newspaper Goteborg Tidning that the sound of the explosion woke him up.

       “It was probably the loudest thing I heard. The whole apartment vibrated. The bed vibrated,” he said.

       Politics

       Gen. Mark A. Milley faces Congress as military controversies mount

       Top military leaders are testifying on Capitol Hill amid a series of controversies.

       Hulten said he saw desperate people who “hung from balconies, climbing over balconies. There was one who fell. It was very dramatic and a very fast course of fire and smoke.”

       Another witness, Lars-Gunnar Wolmesjo, told the Expressen newspaper that he, too, saw people on their balconies. “Some climbed down, some jumped and some had to wait for the firefighters to pick them up with a ladder,” Wolmesjo said.

       Some of the building’s residents jumped out of windows following the blast, Pile told Swedish broadcaster SVT. He said it appeared that the explosion took place in the building’s inner courtyard, which had its entry gate blown away.

       Police have initiated a preliminary investigation. Swedish media said investigators were considering several theories, including a gas explosion or some kind of explosive device left by the gate.

       “We believe that something exploded that has no natural causes,” police spokesman Christer Fuxborg told the Goteborg Tidning.