Bai Li did not assume that meant they were safe. In the apocalypse, a zombie could go from distant threat to immediate danger in less than a second if you gave it enough room to surprise you. So when they reached the first floor, Bai Li slowed her pace and moved toward the building entrance rather than rushing out blindly. She carefully observed the situation outside. The zombies were mobile. Their positions were never completely fixed. Because of that, Bai Li could not say for sure how many were still waiting just beyond the front doors.
