I would suggest you confine them and refer them to the SPCA at
6587 2355 instead of just taking photos.

While kittens may be able to survive outside on their own, and hopefully with enough milk from the mother cat, there is a possibility of them being abused by those with perverted minds, or being run over by cars because they, having wandered into the middle of the road with eyes not yet opened, are unable to escape in time.
There was a recent case of several kittens being tortured to death at Crawford Court along Victoria Street. It was in the Straits Times, unfortunately only given a teeny weeny coverage. Also several years back, there was a newspaper article about kittens being burned alive in a box.
If I did not recall wrongly, I think the SPCA classifies such cases as injured/sick/abused animals. There was an instance where I picked up a kitten at midnight, and the next morning they quickly came and took it.
Even though kittens may be put down at the SPCA, it is actually more humane because kittens that are put down are usually those deemed to be too sick (this I was told by SPCA).
Of course, if you can, please adopt the kittens and sterilize them once they've reached about 6 months of age.