First, back off, consider and observe!
Do NOT "rescue" them: it could be a death sentence.
If they are tiny and alive, there MUST be a mother feeding them. They can die within 24 hours if no mother is caring for them. The mother, if she's not with them, is no doubt out looking for food! An arduous and dangerous task, as she puts her babies at risk from predators and, unfortunately, human "rescuers".
So put some food and water out for mother, and watch and wait.
It is heartbreaking when folks call and say that they found babies, have had them for a day or so (!) and that they're not doing well. It may be too late for these little ones. And dangerous for the mother. Besides the terror, panic, and grief she feels at finding them missing, she is in danger of her milk becoming impacted, and infected, maybe fatally.
Here's a link to some really great information of what to do...from the wonderful Fix Our Ferals site! Please take a look! You may have to cut and paste the link.
It's a tough situation...and each calls for a different plan. It might be best to bring the mother and babies into a safe, quiet place in your home, stressful as it is for mother if she is terrified of humans, and of being confined. No easy answers here: call me and I can help you figure out the best plan.
One thing most rescue groups and shelters do not do, is keep the mother and babies together as long as possible. the babies can be handled, even it the mother is afraid, (I put a barrier, usually a vinyl record cover, between her and them) and mothers and babies should ideally be together for five or six months! the mothers have lots to teach, and the babies need mothering. The longer period makes adoption a bit more difficult, but the kittens can be socialized to humans even when they have a 'feral' mother.