[Simon]

6 is LSPD Interior.

EDIT: I've decided a better name for this interior would be Generic Police Interior. As if you got the co-ords from the LSPD station and set a player to spawn from it you'd spawn inside all fancy and well - but the marker takes you to Red County Police Station; so I assume that the game does something when you enter through the marker to make sure you go out the correct door.

So in short... this "is" the LSPD Interior but it is also used as an interior for other police stations. Spawning in here then walking outside takes you to Red County..