Poor little hedgies. That had to be so hard on their ears.
They'll probably be like that for a day or two. Fire alarms are scary for people, let alone for them. And for half an hour at that. Right now they're still unsure of what happened and are probably worried it will happen again. A few hours' span is not nearly enough time for them to totally be over what happened. I would just go about my normal routine and keep in mind that they need a couple of days to relax again. If there continue to be problems with the alarm, you might look into getting someone to watch them for you until the problem is fixed.
They'll probably be like that for a day or two. Fire alarms are scary for people, let alone for them. And for half an hour at that. Right now they're still unsure of what happened and are probably worried it will happen again. A few hours' span is not nearly enough time for them to totally be over what happened. I would just go about my normal routine and keep in mind that they need a couple of days to relax again. If there continue to be problems with the alarm, you might look into getting someone to watch them for you until the problem is fixed.