You need a distraction. Release the door so that you and Keira can escape.

You're not sure what's going on, but it certainly isn't good. Keira was always a good friend of yours and you can't just leave her there. However, Beth, if it even is the Beth you once knew, is approaching very closely to her hiding spot so getting her out may not be a solution for much longer. You remember that the record room door has a security room override. You hesitate. What you are about to do will almost certainly doom Bob to whatever fate was once awaiting Keira, but you never particularly liked the man anyway. Quickly you punch in the door code on the override console. You see Theresa gesticulate on the camera as the door pops open slightly, then Beth turn excitedly and skip back down the corridor at an impossible pace. You are already moving before you see them reach the room and its inhabitant. You make your way around the corner rapidly and find Keira easily, her face buried in her knees.
"Keira!" You hiss under your breath. "C'mon lets move!" The woman starts, her tear stained features only just visible in the messy crop of her hair. Down the corridor you hear a scream, which is cut short. You grab Keira's hand and jerk her to her feet.
"S-Sarah-" Keira splutters, but you are already pulling her away too fast for the woman to respond. Soon you are out of earshot of the ill fated corridor.
"W-Where are we going?" Keira says when you finally slow to a brisk walk. You breath in deep and turn to give her a hug. She seems surprised for a moment, then embraces you back.
"Out." You say. "We're getting out of here." Keira looks at you as if she is searching for something in your face. Then she nods, swallows and wipes her eyes.
"Ok." She says simply. The two of you turn to make your escape.