"I can guarantee one thing. We will learn the causes of this tragedy and we will do anything possible so that it never happens again," says Greek Prime Minister Kyriakos Mitsotakis as he visits the site of the train wreckage near Larissa, Greece, accompanied by rescue workers and members of the Greek military. Opposition leader Alexis Tsipras who is also visiting the site, speaks of an "unimaginable tragedy" that includes "many young people". In Greece's worst train tragedy in decades, two carriages were crushed and a third engulfed in fire when a passenger train and freight train collided near the city of Larissa. IMAGES AND SOUNDBITES