Foxes

Can anyone share some ideas of how to deter foxes? I had one attack my chickens last sunday in broad daylight. while people were moving about in the garden.

I live in the city so a gun is out of the question.

I would suggest a dog. While foxes can be pretty daring, they are on the low side of the carnivore chain.

Pellet guns are silent, so are an option for city bound people.

They are not fatal, but certainly send a "Not Welcome" message.
This is often even good in rural areas where 'things that go bang' are acceptable.
With the vacuum effect, if you kill a territorial predator, another will move in to fill the void.
By just frightening the animal, he will remain in the territory, and chase off the others.
This is a win/win: he is now trained to leave your yard alone, but will still keep others away from his territory.
He is now your guard.