IRKUTSK, Russia, Oct 23 (Reuters) - A Russian military jet crashed into a residential building in the Siberian city of Irkutsk on Sunday and the two pilots were killed, officials said, the second such fatal incident in six days involving a Sukhoi fighter plane.In a post on Telegram, Irkutsk governor Igor Kobzev said the plane crashed into a two-storey house in the city.He published a video showing firefighters clambering over the wreckage and directing jets of water at the still smouldering rubble.Register now for FREE unlimited access to Reuters.comOfficials said the plane was a Sukhoi Su-30 fighter on a test flight.Videos of Sunday's incident, shared on social media, showed the plane dived almost vertically before crashing in a fireball, sending dense black smoke into the sky."