Part of the building suddenly fell on Friday afternoon, pulling down the scaffolding supporting it, according to local media. The cause is unknown.
Fire and rescue workers pulled the last two bodies out of the rubble on Saturday, meaning that all missing workers were now accounted for.
Two of the victims were from Portugal and Romania, police told Belgian media.
Nine other people were injured in the collapse, three of whom were still in intensive care on Saturday. They were not in a critical condition, Belgium’s fire department tweeted.
The fire department was supported by civil defence rescuers, who used sniffer dogs and a drone to assist in the search for survivors.
Brussels Times reported that the primary school, in the city’s Nieuw Zuid quarter, was due to open in time to welcome pupils for the new school year on 1 September, and that works had been intensified in order to meet that deadline.