NEW : Amnesty International says security forces are blocking access to hospitals . Medical officials say four people died and 26 were injured after clashes in Tripoli . Yemini tribal leaders say they will join protests calling for the government 's overthrow . The Yemen Solidarity Council is comprised largely of member of Saleh 's own Hashid tribe . Witnesses say the victims are anti - government demonstrators .
NEW : Amnesty International says security forces are blocking access to hospitals . Medical officials say four people died and 26 were injured after clashes in Tripoli . Yemini tribal leaders say they will join protests calling for the government 's overthrow . Witnesses say the victims are anti - government demonstrators .