Shadows Creatures in Caves

[Nym Moondown]

Hi, I have a problem with caves. While I was exploring a cave I found a fissure and a shadow creature spawned and attacked me. I know that is normal, but when I hit it another one spawned closeby (the first disappeared and appeared again close to me, but another one joined the fight)...I was down with Health and I run to the surface. After entering the caves again I found the two creatures, hit one, and a third spawned closeby, and again  after (now the creatures  are far away the fissures  but  keep on  multiplying themselves upon one  hit. ).

Is that expected? I cannot fight so many of them, they are 5-6 now. I cannot enter that cave because they are there waiting for me. If expected, any clue about how to deal with the phenomenon? Thx in advance.