velocity components around 35, 45, and 53 km s$^{-1}$ toward our selected physical system. @kohno18 reported the cloud at 58 km s$^{-1}$ as the third velocity component using the NANTEN2 $^{12}$CO (J = 1–0) emission. It appears that the cloud at 53 km s$^{-1}$ reported in this paper is a part of the cloud component at 58 km s$^{-1}$ identified by @kohno18 (see Figure 2b in their paper). In the direction of the W33 complex and the filamentary structures, in the velocity space, the two clouds around 35 and 53 km s$^{-1}$ are linked by lower intensity intermediate velocity emission, which may trace bridge-like features around 45 km s$^{-1}$ (see broken curves around [*l*]{} = 12$\degr$.8 and [*l*]{} =13$\degr$.1 in Figure \[fig7\]a). An analysis of the spatial distribution of molecular gas associated with two clouds around 35 and 53 km s$^{-1}$ shows the overlapping areas toward the filament “fs1" and W33 B (see arrows in Figure \[fig9\]a). These overlapping areas are ablaze with SF activities including massive stars (see Figures \[fig9\]b and \[fig9\]c), where we also find materials with high column densities.

Additionally, a complementary distribution of two clouds (around 35 and 53 km s$^{-1}$) is evident toward the W33 