Secure the landing field | Prologue - The Storm DI Riptide Guide

After a cut scene join the battle, in which you'll be supported by Sam Hardy and few more soldiers. Notice, that you obtain a new weapon - automatic rifle. Firstly, focus on Suicider, a new type of zombies. Don't go too close to him, because he may explode. After that exterminate Walkers and Infested.

At the very end finish off a Thug. It's a small but very tough type of zombies. Fire constantly until it falls.