messagesRef = Firebase(url: "https://"+CONSTANTS.FirebaseDB+".firebaseio.com/messages/1:1000")messagesRef
.queryOrderedByKey()
.queryStartingAtValue(5)
.queryEndingAtValue(10)
.observeEventType(FEventType.ChildAdded, withBlock: { (snapshot) in self.message_list.append(snapshot) });

This is kind of a shot in the dark but it seems like it should work based on documentation here https://www.firebase.com/docs/ios-api/Classes/Firebase.html#//api/name/queryStartingAtValue: