Bangladesh's Prime Minister Sheikh Hasina has resigned and fled the country as anti-government protesters storm her official residence in the capital of Dhaka.br br Student leaders have declared a campaign of civil disobedience to demand that the nation's long-serving leader step asidebr br On Sunday, at least 90 people were killed and hundreds more injured in clashes between police and tens of thousands of anti-government protestersbr br The UN has called for an end to the "shocking violence" and urged restraint from Bangladeshi politicians and security forces.