A heavy explosion occurred in southern Sweden on Friday morning and injured 25, local police said.

Rescue personnel are seen at the site of an explosion in Linkoping, Sweden June 7, 2019. [Photo: TT News Agency via VCG/Jeppe Gustafsson]

Shortly after 9:00 a.m. local time (0700 GMT), a powerful explosion took place in an apartment building containing private homes and company offices in central Linkoping, a city in southern Sweden.

At least 25 people were injured and several dwellings damaged, while the full extent of the damage is yet unclear and the cause has not been reported.

Emergency services, including police and ambulances, have arrived at the scene.

"The only thing we know is that it was a powerful explosion, where it came from is unclear," said Marcus Lundgren, head of the rescue service of Ostra Gotaland County.

Police have blocked off the area, with emergency work continuing. So far, no decision has been made to evacuate any of the impacted buildings.