  We perform a detailed spectral study of a recent flaring activity from the
Flat Spectrum Radio Quasar (FSRQ), 3C\,454.3, observed simultaneously in
optical, UV, X-ray and $\gamma$-ray energies during 16 to 28 August, 2015. The
source reached its peak $\gamma$-ray flux of $(1.9\pm0.2)\times\,10^{-05} \;
{\rm ph\,cm^{-2}\,s^{-1}}$ on 22 August. The time averaged broadband spectral
energy distribution (SED) is obtained for three time periods, namely "flaring
state"; covering the peak $\gamma$-ray flux, "post flaring state"; immediately
following the peak flare and "quiescent state"; separated from the flaring
event and following the post flaring state. The SED corresponding to the
flaring state is investigated using different emission models involving
synchrotron, synchrotron self Compton (SSC) and external Compton (EC)
mechanisms. Our study suggests that the X-ray and $\gamma$-ray emission from
3C\,454.3 cannot be attributed to a single emission mechanism and instead, one
needs to consider both SSC and EC mechanisms. Moreover, the target photon
energy responsible for the EC process corresponds to an equivalent temperature
of 564 K, suggesting that the flare location lies beyond the broad line
emitting region of the FSRQ. SED fitting of the other two flux states further
supports these inferences.
