About 25 people were taken to hospital after an explosion damaged a residential building in the Swedish city of Gothenburg early on Tuesday, public service radio SR reported.
Police said they had opened an investigation. The Sahlgrenska University Hospital spokesperson said three women were seriously injured among the people taken to hospital.
Emergency services said they were working to evacuate people and put out fires in the building.
"Several apartments and stairwells are affected. It is at present unclear what has caused the explosion," the emergency services for the wider Gothenburg area said.
A spokesperson for the emergency services said that several hundred people had been evacuated from the vicinity of the explosion and fire.
The immediate cause of the explosion and fire was unclear. The Nordic country has contended with surging gang crime in recent years, with rival groups employing explosives and firearms to settle scores.

Former US VP Dick Cheney dies at 84
Dozens killed, army helicopter downed as Typhoon Kalmaegi hits Philippines
Trump threatens to cut funds for New York City if Mamdani wins mayoral race
Worker trapped under collapsed medieval tower in Rome dies
Saudi Crown Prince bin Salman to visit Trump in White House
Australia to offer three hours free solar power daily to millions
Man charged with 10 counts of attempted murder after knife attack on UK train
Tanzania's Hassan sworn into office after deadly election violence
