TAD is correct in this. I would ask if an emergency is being declared. If yes send it around, if no then continue. Then both aircraft should be able to complete their flights in a controlled and expeditious manner. As for sending the first around because the second hints that he is low on fuel is quite possibly stupid, ask the first to expedite off the runway, reduce the second to min safe, and all should be well, if not then declare an emergency and then they will get full priority. Simple.