Numerical SPH simulations of supersonic gravo-turbulent fragmentation of a protocluster cloud (1000 M⊙) suggest that the cloud develops a few subclusters (star+gas systems) which subsequently merge into a single cluster entity. Each subcluster carries one most massive star (likely multiple), thus the merging of subclusters results in a central Trapezium-type system, as observed in the core of the Orion Nebula cluster.