NRA range command is cease fire, too, RC. I've gone hoarse yelling it before at a match - you get a bunch of old guys with rifles with hearing aids off, and hearing protection on, and they just DO NOT HEAR YOU!
When I run my safety briefings I train my shooters "if you hear cease fire you WILL repeat it as loud as you can" just so it echos better to both ends of the line.
Of course I have a couple dozen shooters on the line at once, not just one guy, and they're shooting noisy centerfire rifles.
I also take time to confirm no one is downrange and double check with RSO's at both ends of the line just to make sure I'm not missing something. ("ready on the left.." and so on).
There's been a lot of USPSA / IDPA events run without ever having a problem; this is a one in a million deal. But I'm not a big fan of these no-visibility courses. I know it's more exciting to "engage targets as they appear" but it unnerves me because depending on how the stage is set up it can easily violate the "know your target, and what is beyond."
Whether or not the guy got shot downrange, he still got muzzle swept with a gun that had a round in the pipe and finger on the trigger, how many times as that shooter transitioned from left to right and back again?