The woman was doing her stuff like any day. However, she didn't watch the news in which there was a notice that there was going to be some kind of catatrophe (a fallout, war, 2012, zombie and etc). Then, she realized that people were missing so she checked everywhere but couldn't find people because they were hiding/evacuating from the catastrophe. Then, she committed suicide but somehow someone called a phone in the building while she was jumping off. This made her realise that she isn't the only survivor.