Officials in Guinea-Bissau say the situation is "under control" after an overnight attack on the home of President Joao Bernardo "Nino" Vieira.
Military and government sources in the West African country say a group of soldiers fired on the president's home in the capital, Bissau, early Sunday. Witnesses say a gun battle between attackers and security guards lasted several hours before calm was restored.
Officials say at least one person was killed in the fighting, and several others wounded.
There has been no official word on the status of Mr. Vieira, though a Portuguese news agency (Lusa) quotes a diplomatic source as saying "the president is fine."
Senegal's President Abdoulaye Wade says Mr. Vieira called him during the attack. Mr. Wade, who described the attack as a mutiny, says he offered to fly the Guinea-Bissau president out of the country but that Mr. Vieira refused.
The African Union has expressed concern at the situation. AU Commission Chairman Jean Ping issued a statement saying the AU rejects any unlawful change of government, and condemns any attempt to seize power by force.
Mr. Vieira was elected president of Guinea-Bissau in 2005. He previously ruled the country from 1980 to 1999, with the backing of the military.
The attack comes a week after parliamentary elections in Guinea-Bissau. Preliminary results showed a party led by a Vieira ally doing poorly, while, the former ruling African Party for the Independence of Guinea and Cape Verde (PAIGC) won a strong majority of seats.
Guinea-Bissau has experienced considerable unrest since winning independence from Portugal in 1974. Mr. Vieira withstood several coup attempts during his earlier rule before being ousted in 1999. His successor, Kumba Yala was toppled in a 2003 military coup.
Experts say that in recent years, the country has also become a prime conduit for drug trafficking.
Some information for this report was provided by AFP.