Hatzala return to home in car on Shabbos after they complete their life saving task?

 Igros Moshe (O. C. IV #80) Question: A volunteer in the Hatzala organization who leaves his home to save a life on Shabbos when can he return home? Answer: It is a great thing that they do and there is no need to delay and have a non Jew do this.  The main question is if he goes by car to minimize delay. If we require that he wait to the end of Shabbos to return by car, there is concern that it reduces the likelihood he will be available to save another person on Shabbos  Tosfos has a principle that we allow things sometimes to avoid an undersirable consequence of prohibition regarding saving life.  Rambam also rules that someone who goes to rescue his fellow Jew from attack on Shabbos is permitted to return home afterwards with his weapons on Shabbos in order to ensure that in the future people will be willing to help on Shabbos.