Natasha clears all the entrances and exits before allowing herself to catalogue the carnage at her feet.
There had probably been a neater way to kill them all. But they'd caught her by surprise (a rarity, she was going to have to figure out how they did that and make sure it never happened again), and the closest weapon had been a knife.
So she slit their throats.
Everything's drenched in red now: the floor, her clothes, her hands.
She'll have to get somewhere secure and soak the clothes in cold water if she wants to wear them ever again.