BU33 looks like it might be a fighter/trainer aircraft. This would chime with it being in a formation of 3 or 4.
That flight trackgoes up to the Dutch islands of Texel & Vlieland where there are weapons ranges.
Looking more like a fighter training flight with some nav exercising and wepons work on the ranges.
Gut reaction to this crash is that it is probably an accident.
Most plane crashes happen during take-off & landing.
The fact that it crashed on a football field suggests that it had a major problem & the football field was the largest flat open area to attempt an emergency landing.