<Tr> <Td> (Full screen) </Td> </Tr> <Tr> <Td> Location of the accident in relation to Humboldt, Nipawin and to nearby cities of Saskatoon and Prince Albert </Td> </Tr> <P> On April 6, 2018 at the intersection of Highways 35 and 335 near Armley, Saskatchewan, sixteen people were killed and thirteen injured when a westbound semi-trailer truck was struck by a northbound coach bus . The semi-trailer had failed to yield at a flashing stop sign . The bus was travelling at a speed of approximately 100 km / h . Most of the dead and injured were teenagers from the Humboldt Broncos, a junior ice hockey team that plays in the Saskatchewan Junior Hockey League (SJHL). </P> <P> Across the country, the crash prompted condolences from public figures and celebrities, vigils, and tributes, such as people leaving hockey sticks outside their doors . A GoFundMe crowdfunding campaign set a national record by raising over $15 million . </P>

What was the cause of the humboldt broncos accident
find me the text answering this question