There are two doorways, but my understanding of the situation is that the door we came through leads to more shooting, and there are booted feet moving around on the other side of the other door. We're not trapped, but we need to go through potentially hostile folks to get to Kellon, and soon.
As I understand it, the boot sounds are coming from the cantina that you just left, from behind the closed door you just crossed and closed. You haven't been to the other door, the open one, at the other end of this room through which smoke is escaping. From this second door is coming "a loud sparking sound" though it's unclear what the sound is or where exactly it's coming from.
I just did. You were waiting in ambush and I pointed out that you could just leave through the other door. Waiting until after you'd shot the people coming through the door would have been waiting too long.