ADEN - Firefights between police and southern separatists in Yemen on Friday killed five and wounded 23, as protesters nationwide denounced a plan granting the president immunity from prosecution, medics and police said. “Three protesters were killed and 18 others were wounded,” a medical official in the main southern port of Aden said of the southern separatists. “Two policemen were killed and five others were wounded,” said another medic from a government hospital in the city. The official named one of the dead as Major Walid Saleh Ali, whom police had earlier said was among two policemen wounded. Witnesses said police used tear gas and live rounds against thousands of demonstrators in Aden’s Khor Maksar district.