Be sure that the mother is feeding the kittens and if not try to hand feed with a bottle. Many feral cats have diseases that can attack weak immune systems.
Is the mother taking care of them? They may not be getting the nutrients they need. They may also have something genetically wrong with them. Please take the kittens and the mother to the vet immediately. They may be able to save the kittens and discover what's wrong. Please do this as soon as possible.
There could be several reasons. The mother is not providing milk for it, they may have an infection or birth defect, it is not strong enough to make it to the mother for feeding. You should consult your vet immediatly.
The most common reason for early death in kittens, particularly at this time of year, is fleas. Lift thier lips. If their gums are light pink or white, they are anemic (low blood) from fleas draining their blood supply.
This could be because they might not be well kept. Another reason could be if you give them a shot try not to put it in there body try to stretch the skin and inject it that way because most of the time people don't know what they are doing.
