What is the setting of Killers of the Dawn by Darren Shan?

The novel is set primarily in the underground tunnels where the Vampaneze live. The setting also includes the city that lies directly above the tunnels. The novel seems to be set in the future. The main characters are involved in the War of Scars, which is a battle for control between the Vampires and the Vampaneze, which are the purple-blood cousins of the Vampires.