A bus struck and killed several people on Friday late afternoon in central Stockholm, also injuring several others, Swedish police announced.

The double-decker bus crashed into a bus shelter, according to images from Swedish media showing a large number of ambulances and emergency vehicles at the scene.

The cause of the accident is still unknown, said police spokesperson Nadya Norton to AFP.

"The investigation will have to determine what happened. It is too early to say anything, and I do not want to speculate", she said.

The bus driver has been taken into custody and an investigation for involuntary manslaughter has been opened, as per standard procedure, she added.

"We need to question him, and then we will see whether he will be released or placed under arrest", Ms. Norton continued.

This is a developing news story, more information to follow.