I feel so sad for what happened to you and your cats. Saya faham sgt2 how you feel. Kejadian yg sama pernah terjadi to me but luckily yg kene langgar tu tak mati but my neighbor yg langgar (or so says my other neighbor-tak tau betul ke tak but rasanya ye) and then buat tak tau. The least you can do is inform the owner and mintak maaf. I had one cat pun mati kat taman, I thought dia tido gak but tgk dekat dah penuh dgn semut. There's only one thing I suspect kalau kucing mati2 tiba2 mcm tu...dia makan racun in which I think org sengaja letak utk bunuh die.
3 ekor skali gus...so sorry for your lost. My heart goes out to you. Semoga kucing hitam akak slamat dan akan pulang soon.