How to make an area that only players can access?

I am working on a game that consists of a maze with a killer NPC inside it. I want to include safe rooms in the maze where keys etc. can be collected and also as a place to hide from the NPC.

How do i make a wall or block that only players can pass through so that the NPC cant follow them into the safe room?

I have seen posts about making parts that delete for the client but still stay on the server but how would i script this?

Thanks!