Complex sentence: On 22 March 2016, at least six explosions occurred in Brussels, Belgium; two of which were at the Brussels Airport and three occurring in the Maelbeek/Maalbeek metro station.
Split into simpler sentences: On 22 March 2016, at least six explosions occurred in Brussels, Belgium two at the airport and three at the metro. Two were at the Brussels Airport, and three occurred in the Maelbeek/Maalbeek metro station.