The girl's questioning expression was unmistakable. Hannah shrugged. "It wasn't safe to stay where we were," she said. She paused, listening with her full attention, but the distinctive sound of the replicators scuttling around was absent from this building--for the moment.
"You should be safe enough here on the rooftop for a while," she told the girl. "But, if you need to get down, or want to leave..." She walked over to the blockhouse that sheltered the stairwell. The door was locked, as she'd expected.
Hannah yanked the doorknob off and removed the bolt. Now the door could be pulled open by reaching through the hole. "If you want to leave," Hannah repeated, turning back to the girl, "you can use the stairs."
She looked out over the edge of the rooftop. She could see and hear other people who needed help against the replicators. "I need to go," she said. "Are you going to be okay here on your own?"