that allowed us to perform a detail spectroscopic study. The top row of Figure \[fig:prof\] displays the line profiles before (black) and during (blue) the event in  1335 & 1336 [Å]{} and  1394 & 1403 [Å]{}. We fitted all the line profiles with a single Gaussian for further analysis. Figure \[fig:prof\] plots the extracted parameters from fitted Gaussians such as intensity (second row), Doppler velocity (third row), and line width (fourth row). Doppler velocity is estimated with respect to the pre-event conditions. Intensity curves (second row) for both and (both the lines) show intensity enhancements by the factor of more than 35, and 100, respectively, during the event. We also note that several pixels were saturated at time 13:03:56 UT in both the spectral lines indicating the epoch of peak intensity, which was attained within 40 s of its start time as was also inferred from the IRIS-SJIs taken in 1330 [Å]{} and 1400 [Å]{}.

![Same as Figure \[fig:temp\_A\] but for the loop-top.[]{data-label="fig:temp_top"}](fig12.eps){width="48.00000%"}

![image](fig13.eps){width="85.00000%"}

![image](fig14.eps){width="85.00000%"}

During the event, both the spectral lines of and show strong redshifts i.e., downflows of $>25$ km s$^{-1}$ and $>20$ km s$^{-1}$, respectively. The spectral line widths also increased from $\approx32(40)$ km s$^{-1}$ in the 