Armed officers blocked traffic while a helicopter hovered over the scene of the incident in the Forest district, an AFP journalist said.
In 2016, the district was the scene of a shootout with police involving Paris attacks suspect Salah Abdeslam that led to his capture three days later.
A local police spokesman told AFP a Polish man had gone to a local shop Thursday "and said that a murder had been committed at a local residence.
"The residence was visited and there was nothing. But other people spoke of a disturbance nearby."
Local mayor Marc-Jean Ghyssels told broadcaster RTBF that police were called because of the "presence of armed people in a building."
"At this stage it seems to be a private dispute. There is absolutely no link with terrorism," he said.
Belgium recently lowered its terror alert to its second lowest level, nearly two years after the Brussels airport and metro suicide attacks.