JOHANNESBURG—Rebels fought the Mozambican army Sunday for the fifth straight day for control of the strategic northern town of Palma, as reports came in that dozens of civilians have been killed and bodies were littering the streets. The fate of scores of foreign energy workers was also unknown. Some of the dead had been beheaded, according to Human Rights Watch. An attempt by expatriate workers to flee to safety came under heavy fire, causing many deaths, according to local reports. The battle for Palma highlights the military and humanitarian crisis in this Southern African nation on the Indian Ocean. The three-year insurgency of the rebels, who are primarily disaffected young Muslim men, in the northern Cabo Delgado province has taken more than 2,600 lives and displaced an estimated 670,000 people, according to the U.N. The attacks in Palma started Wednesday just hours after the French energy company Total announced that …