The Warriors: Crimson Chaos - The Warriors, #1

Trigger warning: Animal (dog) death. Eight teenagers with powerful, supernatural abilities must undergo training by the eccentric mystic Chinook to wage war against Tutock, the god of evil, before San Francisco falls into his hands permanently. But Flash Michaels, Thunder Copiel, Shades Thopho, Scorpio Lapine, T-boz Rabbiel, Snow and Ice Thornton, and Chilie Davids are inexperienced and uncooperative.
They have only less than one year to prepare for their first battle, except Tutock's power is increasing and their fears and distrust may allow the god to get what he desires. They must find a way to overcome their fears and defeat the god by participating in the dangerous training whether they want to or not.