BERLIN: Three men and a woman were injured in a shooting outside a shisha bar in Berlin, police said Monday, with media reports saying some 30 shots had been fired.

“The background of the attack is still unclear,” police said in a statement.

The shooting erupted at around 11:00 pm on Sunday, and one man was hit at least eight times in his upper body, German media reported. But no one suffered life-threatening injuries.

The wounded were all either Serbian citizens or had Serbian background. No one has been arrested over the crime at Muellerstrasse, a busy thoroughfare in a working class district in northwestern Berlin.

Tagesspiegel daily quoted unnamed investigators saying that the four victims were standing outside the shisha bar when they were hit by shots fired from a car that was driving by. In February last year, a gunman with suspected far-right beliefs shot dead nine people at a shisha bar and a cafe in the city of Hanau, about 20 kilometres (12 miles) east of Frankfurt.

Shisha bars, where customers can smoke tobacco through special pipes, are popular in many German cities.