If you are in an apartment building chances are you are not the only one home all day long. In the event of an emergency go out and the hall and scream I need help with kids and pray that someone comes and offers to help. If you put them all in a stroller and do the same someone may help you carry them down the stairs. I would contact your fire department and ask their advice - which will be good to have on hand to show parents. For sure find out what level their ladders can reach. If your level then put them in the stroller and go out on the balcony and wait for help - but in the grand scheme of things unless smoke enters your apartment keep the door shut and stay by the balcony. You might consider making a sign to hang on the outside of your day when the alarm goes off that says kids inside help needed. You might also want to talk with your landlord and find out the possibility of moving to a lower floor if a place comes available as the safety of the kids will reflect badly on them too if anything happens.