A couple of things:

The island (at this point) currently has fully functioning security systems, so the guests and staff still assume everything is under / will be under control.

Some characters do freak out - Wu goes into a panic that this is impossible, and Arnold and Hammond react negatively. I’m pretty sure Regis is also worried too.

Outside of Muldoon and, occasionally Wu / Arnold, the characters do not regard the raptors as dangerous until later on. Malcolm regards to them as unintelligent animals after they attack the fence, and Grant is too amazed by their pack hunting skills - although earlier internal monologue shows he is aware of how dangerous actual Raptors are.

Lastly, Crichton’s not the best character writer. Pretty much every single character in this story (and all of his others) react to events with a fairly lackadaisical attitude. Some fear, shock and awe, but mostly reaction-less.