[Pieter H]

Assuming dat (14/5), timing (around 9.50 a.m.), area (Vilvoorde, N. of Bruxelles) and 4 crew are correct, I think this one is the only candidate
(original entry from Peter Cornwell with my additions):

7./KG27 Heinkel He111P. Damaged in attacks by Nos. 85 and 87 Squadron Hurricanes during sortie over Leuven and also hit by AA fire. Crash-landed south of Brussels 9.30 a.m. FF Fw Willi Biskupski captured wounded. Uffz Willi Heidbüchel, Uffz Josef Kerstin, and Gefr Arthur Klöckner baled out and captured unhurt. Aircraft 1G+HR a write-off.

If your info is correct it would mean that at least the crew baled out north of Bruxelles. Maybe the "south of Brussels" of Peter then refers to the crash site of the aircraft.

Pieter