Ellie had made her move under the presumption that there was only one; she'd been thinking of Brennan's gun, and how it'd be easier for him to fire knowing she was out of the way.
For the space of a few seconds, she tucked herself as far back against the wall as she could, ready to spring if the door opened -- but nothing happened.
There was the sound of shots, more footsteps, the screams and growls of the undead; then Brennan's voice. More shots.
It was fairly clear at that point what Ellie had to do. She couldn't tell what she'd see when she opened the door again, but there was no time to waste considering it. No matter what, she had a responsibility toward Brennan and Brennan's safety, and she wasn't the kind of person to give something like that a second thought.
She pushed open the door, holding it against herself with one hand as a makeshift shield -- but there were no more runners left coming through the door. They were darting toward Brennan, circling him, almost pushing eachother over in their eagerness.
He was a good shot.
Eloise knew it was a gamble to engage any of them by hand, but she didn't know what else to do, how else to help. It was too dangerous to assume he could take them all at once, now that they were closing in -- even without any sense of organization. Ellie had never seen zombies attack eachother, but these runners seemed oddly on edge. She didn't want to get shot by accident, either. His weapon was most effective between both of theirs.
So she took a step out of the cabinet.
"Hey! HEY! Me, look at me!"
Ellie had no idea if zombies had any concept of choosing a target. She wasn't sure if their instinct to kill was supplemented by any form of intelligence, even on a subconscious level. The runners, however, did exactly as she asked -- they looked at her, and the next moment they were coming for her.
She began taking quick steps backward to the cabinet (her plan had been to close the door again) but didn't have time before one leapt forward, attacking; reflexively Ellie stabbed with the blade, catching it below the eye -- but it barreled into her, conveniently pushing her into the back of the cabinet.
The space was narrow enough that other runners weren't able to reach Eloise, but the runner she'd engaged was large, taller than she was; he'd knocked the wind out of her. She could hear herself wheezing as she pushed away his hands, struggling to pull the machete out of his skull and strike again.