Two people were fatally injured in a dispute in a café in the Belgian city of Eupen.
Five more were injured, some seriously, early on Friday morning, the police said, according to the Belga news agency.
The injured are therefore other guests and employees.
According to the information, a knife was also used in the dispute and a 52-year-old suspect from the Belgian municipality of Baelen was arrested.
The background and the motive for the crime were initially unclear, as Belaga reported.
An examining magistrate is investigating murder and willful assault.
Eupen is located near the German-Belgian border, around 15 kilometers from Aachen as the crow flies.