VLA NH₃(1, 1) and NH₃(2, 2) channel maps towards OMC-2 FIR 4. Contours start at 5σ and increase by steps of 5σ. The 1σ rms values are 5.0 mJy beam^-1 for NH₃(1, 1) and 4.7 mJy beam^-1 for NH₃(2, 2). The velocity of each channel is marked in the top-right corner of each panel in units of km s^-1. Red crosses mark the positions of the three sources identified in this work (see Table 4). Green circles mark the position of FIR 3 (NE) and FIR 5 (SW) according to the 1.2 mm observations of Chini et al. (1997). The bottom-right ellipses in each panel represent the beam sizes.