People really need to stop believing what they heard about foxes when they were being read bedtime stories.
Foxes don't kill for pleasure, they kill for food and, being intelligent creatures, will store (or cache) additional meat in the knowledge that they will be able to eat it later.
They're far less a risk to children than the family dog - they're less likely to trip them up coming down the stairs, for a start - and it's not their fault stupid humans put some of their natural food sources (rabbits, rodents, poultry) in shabby little cages and boxes with fuck all protection or create other food sources by running over cats with their cars or by putting carrion - as in chicken carcasses and the like - in flimsy plastic bags on the street.
Like all wild animals (and cats, dogs, sheep, cows, horses, fwuffy ickle bunny wabbits...), they may bite if frightened, trapped, wounded or if their young are disturbed or put at risk.
The only murderous little bastards in the equation are humans.