Fear the Walking Dead: Passage: Part 5

Gabi and Sierra enter a construction site. Sierra is wondering how far it (the tunnel) is, and Gabi assures her that it isn't far. They round some construction equipment and are confronted by a chained up infected. Gabi freezes, but Sierra urges her on, telling her that now would be a good time to try out her skills with the knife. Gabi raises her knife, but before she can strike, a gunshot rings out and hits the infected.