But Salah Abdeslam – believed to be the crazed gunman behind last Friday’s massacre in the French capital – is still on the run.
The 26-year-old was let go by police after being stopped at the Belgium border just the hours after the attacks.
Abdeslam – the world’s most wanted man – is reportedly wearing a wig and glasses to avoid being detected.
A total of 19 houses were searched in central Brussels – plus three in Charleroi, a city in the south of the capital.
Police fired on a vehicle in Molenbeek but it is not clear if those inside were connected to those being sought.
Prosecutor Eric Van Der Sypt said: “We can stress that no weapons or explosives were found. Abdeslam Salah was not found during the raids.
“Sixteen people were detained. The judge will decide tomorrow whether they will be held further.”
Brussels has been on lockdown since Friday after reports of an “imminent” terror attack by Islamic State fanatics.
Prime Minister Charles Michel said the alarm had been raised “following information of a risk of a Paris-style attack by individuals with arms and explosives”.
Schools, universities and the underground system will remain shut – and workers have been ordered to stay at home.
The Great Britain tennis team has delayed its departure for next week’s Davis Cup final – due to be played 35 miles north east of Brussels.
Read more: express.co.uk