Can they see arround the area from the loft, i.e have they got a flight?
If they have they should be fine, just open the loft and allow them to come out in there own time, don't be tempted to make them come out and fly etc.
If they are hungry the first time even think about sitting in front of the loft and let the birds come out to you, throw the odd grain or 2 down for them and they will come for the food and have a good look, the when you want them back in call them in with the food. This way you will be there to prevent the birds being startled by anything like cats etc and you can keep the birds quiet and under control.
Phil