Togo President Gnassingbe Eyadema died of what aides said was a heart attack Saturday, and the military immediately named his son as his successor. Eyadema, 69, who claimed sole control in 1967 after aiding in what was sub-Saharan Africa's first postcolonial coup four years earlier, suffered a heart attack in his southeastern hometown of Piya early Saturday, officials said. Within hours, Togo's military high command declared Eyadema's 39-year-old son, Faure Gnassingbe, was the West African nation's new president. While the constitution calls for that power to go to the speaker of parliament, Togo's military said the lawmaker was out of the country and that it acted to avoid a "total vacuum of power." State television showed military leaders, including army chief of defense staff Gen. Zakari Nandja, swearing allegiance to the late leader's son, who was the minister of mines and communications. Prime Minister Koffi Sama called upon security forces to keep law and order. He also announced all land borders and air space in the nation of 5.5 million people had been closed, along with the international airport in the capital, Lome. "The armed forces and police must help preserve peace and national security," Sama said on state radio. "All the country's political, social, religious leaders must avoid any act likely to plunge the country into anarchy and confusion." In Washington, State Department spokesman Edgar Vazquez extended condolences to Eyadema's family but also encouraged the country to embrace a more representative democracy. "The United States has long encouraged Togo to move toward a full and participatory democracy and it continues to believe that this must be the goal for the people of Togo," Vazquez said. By law, the parliament speaker must call national elections to choose a new president within 60 days.