Re: OOC
It's hard to say in this situation. The adventure has a lot of combats like this, and for some reason, the Romulans are unwilling to negotiate under any circumstances.
I was thinking on the following things: you were the ones to beam down to their actual position, and you were the ones who startled them. While shooting is overreaction, it's more of a suppresive fire rather a normal firefight. That's why the others asked if the shooting order still stands, since while it's not against any convention to attack fleeing enemies (it's considered manouvering, not surrendering), I think Klingons would think of it as dishonorable, and Federation as either immoral, or unnecessarily harsh (mostly DS9, Sisko did not even order to shoot the Jem'Hadar until it was inevitable to fight with them). Also, since the Romulans have a highly militaristic worldview, high chance they would be shooting at the opposite case! In any way, it could be a good unforeseen dilemma, to decide if it's OK shoot fleeing enemies in the back.