By Francis Kokutse and Krista Larson
Ghana's vice president has taken the presidential oath of office just hours after officials announced the country's leader had died.
President John Atta Mills died Tuesday at a military hospital before he could finish his first term in office. He had planned to seek re-election in December's poll.
State-run television in Ghana carried John Mahama's swearing-in live from parliament Tuesday evening. He raised a golden staff of office above his head.
The swift adherence to Ghana's constitution on succession underlines the country's reputation as one of the most mature democracies in the region.
Atta Mills took power in 2009, marking the country's second successful handover of power from one legitimately elected leader to another.
Ghanaian state-run television stations GTV and TV3 broke into their regular programming to announce the president's death, which comes three days after his 68th birthday.
Chief of Staff John Henry Martey Newman told the nation that Atta Mills had died Tuesday afternoon at the 37th Military Hospital in Accra but gave no details about the cause.
"It is with a heavy heart and deep sorrow that we announce the sudden and untimely death of the president of the Republic of Ghana," Newman said.
Information Minister Fritz Baffour later confirmed that Atta Mills had died but also declined to comment further.
Louis Agbo, a university student in Accra, said the television stations interrupted regular programming to announce Atta Mills' death and he was shocked by the news.
"I could not even shout or cry," Agbo said. "I rushed outside and saw people crying and wailing on the street."
The nation stood by for a speech by Vice President John Mahama, who will become president under the nation's laws.
Chris Fomunyoh, the senior director for Africa for the Washington-based National Democratic Institute for International Affairs, said that Ghana's democracy could weather the death of a president.
In other nations in West Africa, the death of a ruler usually spells a coup, as it did in neighbouring Guinea following the 2008 death of longtime dictator Lansana Conte, and Togo, where the military seized power after the president's death in 2005 in order to install the leader's son.
"Ghanaian democracy has been tested and its institutions function well," said Fomunyoh. "There's no reason to think that Ghana and its democracy will not handle this event properly."
Ghana, whose economy has been fueled by gold, cocoa and timber exports in the past, hopes to put its oil money to good use, mindful of how nearby Nigeria suffered through military dictatorships and widespread corruption over its oil wealth.
Atta Mills was elected in a 2008 runoff vote - his third presidential bid - after campaigning on a platform of change, arguing that the country's growth had not been felt in people's wallets.
"People are complaining. They're saying that their standard of living has deteriorated these past eight years," he told The Associated Press in 2008. "So if Ghana is a model of growth, it's not translating into something people can feel."
Atta Mills even put up campaign posters of himself standing next to a cutout of US President Barack Obama in an effort to emphasize that he too stood for change.
Atta Mills had travelled to the United States in March where he met with Obama. The Ghanaian leader also travelled to the US in April as well, as rumours about his health began to circulate Ghana. Opposition newspapers had recently reported that he was not well enough to run for a second term.
A government official in neighbouring Ivory Coast said that he saw Atta Mills around six months ago in Ethiopia during an African Union meeting.
"We are hearing that he died of cancer of the throat. I saw him in Addis Ababa - not this meeting, but the one maybe six months ago," said the official, who requested anonymity because he was not authorised to speak to the press. "He was walking slowly. I am surprised to learn that he is only 68. He looked much older."
Still, the official said no one suspected he was gravely ill. "Yes, his death is a surprise - it's six months before the election, and he was a candidate."
Atta Mills won the 2008 second round ballot capturing a razor-thin victory with 50.23 percent of the vote - or 4,521,032 ballots. His opponent, Nana Akufo-Addo, garnered 49.77 percent - or 4,480,446 votes.
Atta Mills also served as vice president under Jerry Rawlings, a coup leader who was later elected president by popular vote and surprised the world by stepping down after losing the 2000 election.
Atta Mills spent much of his career teaching at the University of Ghana. He earned a doctorate from London's School of Oriental and African Studies before becoming a Fulbright scholar at Stanford University in Palo Alto, California.
AP