Foxes will eat mice, rabbits, plus assorted berries and bugs they bump into while out hunting, but they really, really like chicken... I guess if you are in an urban area then probably your neighbors don't raise chickens in coops in their yards... ??
A problem with foxes is that they can carry rabies. The disease can be transmitted by contact with an infected animal's saliva, across species, so that an actual bite is not necessary. If your neighbors have outdoor kitties and have not protected them against rabies then I would mention the presence of the foxes to them so they can get their cats vaccinated immediately. Rabies is not a pleasant way to go, for critters or people.
As others have mentioned, the foxes should be wary of people, not approaching them. If they approach, bad news, probably sick.