Schematic cartoon of OMC-2 FIR 4 and the nearby OMC-2 FIR 3, summarising all the physical elements in the region that we propose according to the data presented in this work (see Sect. 4). The white ellipse inside the main source depicts the ionised region powered by a B4 young star. The colours of the main, west, and south sources represent their systemic velocities with respect to the nominal value for OMC-2 FIR 4 (V_LSR = 11.4 km s^-1), marked in green. The small red and blue circles within the three sources represent the possibility that they harbour smaller unresolved molecular condensations, with the colour blue denoting a colder temperature than red.