Check out this video, German SEK, trying to take a guy into custody. I do not care about the reason why, I care about the tactics.
The SEK guys do a "run-by" first guy completes a task, in this case, smashing a window, which allows the second guy (and third guy who ran away initially) to access the person. The bad-guy throws the old I have a gun wrench into the equation and causes the contact SEK operator to backpedal. What happens? He "tactical back-rolls" and was close to putting a bullet into his foot. Thankfully it looked like he has practiced this before, he used his momentum to sit on his ass, compressing a leg and straightening another leg, then rolled backwards.
What's the lesson here? Do not backpedal and do not backup while shooting - you will not be paying attention and unless you are slowly moonwalking, you will trip.