embedded structures on large-scale areas. In this paper, using a multi-wavelength approach, we aim to explore the ongoing physical processes in the extended physical system hosting W33. In particular, this observational work focuses to understand the formation mechanisms of massive stars and clusters of YSOs. In this connection, the study of molecular gas toward our selected extended system has been carefully carried out using the FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope [FUGIN; @umemoto17] $^{13}$CO(J = 1–0) and C$^{18}$O (J = 1–0) line data.

The present paper is organized as follows. The information of the adopted data sets is given in Section \[sec:obser\]. In Section \[sec:data\], we present the observational findings derived using the multi-wavelength surveys. We discuss the possible SF processes in Section \[sec:disc\]. Finally, the main conclusions of this paper are presented in Section \[sec:conc\].

Data sets and analysis {#sec:obser}
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With the aid of the spatial distribution of 88 ATLASGAL clumps at a distance of $\sim$2.6 kpc, the selected target area ($\sim$1$\degr$.1 $\times$ 0$\degr$.815 (or $\sim$50 pc $\times$ 37 pc); centered at $l$ = 12$\degr$.946; $b$ = $-$0$\degr$.192) around W33 is presented in Figure \[fig1\]a. Table \[ftab1\] gives a summary of various multi-wavelength 