Imaam completed Maghrib Salaat after two raka’ts

Q.  The Imaam completed Maghrib Salaat after two raka’ts. Although the muqtadis drew his attention by exclaiming ‘Subhaanallaah!’, the Imaam ignored them and continued to complete the Salaat. Some muqtadis did not follow the Imaam and completed the third raka’t. Is their Salaat valid?

A. No one’s Salaat is valid. The Imaam and the Muqtadis have to repeat their Salaat.