[WalterBright]

Go out a different window.

It makes sense to keep a fire axe in your apartment, so you can make your own doorways/windows as needed in a fire. Also good against zombie attacks.

[rsynnott]

In a large high-rise, the majority of apartments will only have windows on one side (unless there's an inner core or something).

[WalterBright]

I wasn't clear about what to do with the fire axe - go into the hall, and cut through the door to an apartment on another side.

Fire axes are designed specifically for that sort of job.