Five of the seriously wounded, who include two minors, are in a critical condition.
Five of the seriously wounded, who include two minors, are in a critical condition, Belgian prosecutors said in a statement.
Police first spotted the vehicle early Tuesday driving on the wrong side of the road about 40 kilometres (24 miles) south of Brussels, and a car chase ensued.
All the victims were illegal migrants to Belgium, the statement added.
Police said the driver of the van was under arrest and would be questioned later in the day.
Belgium is a major transit point for human traffickers who arrange to move illegal migrants across the English Channel to Britain.