to two colliding clouds/flows [e.g., @haworth15a; @haworth15b; @torii17]. Furthermore, one may also observe a complementary spatial distribution of two clouds in the CCC site [e.g., @torii17; @fukui18; @dewangan18x; @dewangan19a], which is related to the spatial fit of “Key/intensity-enhancement" and “Cavity/Keyhole/intensity-depression" features.

In the direction of the W33 complex (area $\sim$15 pc $\times$ 15 pc; see a broken box in Figures \[fig1\]a and \[fig1\]b), @kohno18 proposed the CCC model to explain the formation of massive stars. They found complementary distributions of two clouds (at 35 and 58 km s$^{-1}$) around the W33 complex. These authors also computed the timescale of the collision between these two clouds (i.e., 0.7–1.0 Myr), which was found to be older than the dynamical timescales of the outflows in W33 Main and W33 A [i.e., $\sim$10$^{4}$ yr; @kohno18]. They concluded that the sources in the W33 complex (i.e., W33 Main, W33 A, W33 B, W33 Main1, W33 A1, and W33 B1) were formed in the dense layer produced via the collision event. One can note that previously, no attempt was made to examine the wide-area around the W33 complex, which has been carefully carried out in the present paper.

In the present work, we have detected three 