You make the decision you want to flee from an attacker. You'll have to add detail depending on context, obviously.
* GeneralTrivium attempts to run from [target]
Then you wait for their reaction. They may stop you, they may not, they may just pull out a weapon.
After that reaction you can actually start running.
You were perfectly in your right to start running after he dodged your attack. He's also in his right to start shooting at you, because he dodged your attack.
However, depending on the distance and how experienced he is with weapons he should have-
A) Had his weapon knocked out of his hands
or
B) Shot to miss.
If you started running
after he did his /me of dodging the attack, then that's not mingerunning.
He can be guilty of playing to win however. He's a citizen with probably limited weapons experience, and also underfed, meaning his reactions wouldn't be so good as to dodge your attack.