In Underworld Blood Wars, Varga started shooting all the recruits who witnessed the cage fight between him and Selene.
But there are no facial expressions on the new recruits, this scene looks a lot like this question.
Actually this scene lasts for a few seconds which is enough for us to notice stoic facial expressions.
He's using his vampire speed. The bloodlings are too young to have developed super speed and can't react very quickly.
Just like this movie did to the audience.
You can see that it takes seconds for Vagra to kill everybody, only one really has time to run and panic. Hilariously.
16 seconds at slow speed. Speed it up on youtube to 1.5x speed, and it seems more natural, and we see normal speed reactions. It's really should be about 1.75x speed.
They look stoic because they are stunned and have not processed the situation yet.
Sidenote, you can't expect nameless extras to have the same emotional range of paid actors.
