Several shots were fired in the parking lot of a hardware store on Kapweg in Berlin-Wedding on Friday afternoon.
According to the fire department, there were four injured, three men and one woman.
They were medically treated on site and then taken to the hospital, according to a fire department spokesman.
Two of them were stabbed and another was gunshot.
The fourth man was only slightly injured, writes the Berliner Tagesspiegel.
The police and fire brigade went on a large-scale operation.
The operation is still ongoing, said the Berlin police on request.
Details about the background are not yet known.
According to a dpa reporter, the crime scene is still cordoned off, the police asked a number of eyewitnesses about their observations in order to reconstruct the course of events.
There are still numerous police forces at the scene, including patrol and criminal police.