Complex sentence: A mother and her four children, ranging in age from 6 to 14, were found dead in the third house where when the demolition charges failed the attackers had used sub-machine guns and grenades.
Split into simpler sentences: A mother and her four children, ranging in age from 6 to 14, were found dead in the third house. When one of the demolition charges failed the attackers used sub-machine guns and grenades.