Renegade soldiers in Mali have looted the presidential palace in the capital, Bamako, after a coup.
The coup leaders have called for calm and said all borders are closed after announcing that they have seized control of the country on state TV.
A government official told the BBC that President Amadou Toumani Toure is safe and not in the custody of mutineers.
The African Union said the "act of rebellion" was a "significant setback for Mali".
Kenya's Foreign Minister Moses Wetangula and his delegation are stranded in the country, as Bamako's airport is closed, after attending an AU meeting on peace and security.
The West African regional body Ecowas said the mutinous soldiers' behaviour was "reprehensible" and "misguided".
The soldiers, calling themselves the Committee for the Re-establishment of Democracy and the Restoration of the State (CNRDR), said they would hand over power to an elected government.
"The objective of the CNRDR does not in any way aim to confiscate power, and we solemnly swear to return power to a democratically elected president as soon as national unity and territorial integrity are established," they said in a statement.
The soldiers said they had led Wednesday's mutiny because the government had not giving them enough arms to tackle a rebellion by ethnic Tuareg in the north of Mali.
They attacked the presidential palace, traded gunfire with soldiers loyal to the government and took over the state radio and TV broadcaster in Bamako and took it off air.
After several hours of footage of traditional Malian music and dancing, a group of soldiers appeared on screen early on Thursday morning.
The leader of the mutiny was revealed to be Capt Amadou Sanogo, who appeared briefly to announce the imposition of a national curfew, although he did not specifying the time and said the constitution had been suspended.
The BBC's Martin Vogl, who is in the capital, says soldiers were seen taking televisions and other goods out of the palace following the coup announcement.
Our correspondent says it is possible that the coup may falter, pointing out that the mutinous troops are poorly equipped, led by a mid-ranking soldier and they do not have the backing of all Malian forces.
The well-trained and organised Red Berets unit is loyal to the president and he is believed to be under their protection, our reporter says.
If those officers decide to push back, they could perhaps overturn the coup, he says.
In a second statement, read on state television on Thursday morning, the renegade troops called on soldiers who took part in the mutiny to stop shooting in the air in order to restore calm in Bamako.
They announced that all borders were closed and asked for civil servants to resume activities next week.
A source told the BBC that the foreign minister and a number of other ministers have been arrested by the renegade soldiers.
A government official, who told the BBC the president was safe, did not give any further details about his whereabouts.
Meanwhile, in the northern town of Gao, renegade soldiers said they had detained loyalist military chiefs in military barracks, according to the AFP news agency.
Mali has had democratic rule for the last 20 years, during which it has come to be considered as a model which other emerging democracies can look to.
The unrest began on Wednesday as the country's defence minister started a tour of military barracks north of the capital.
Soldiers upset with the government's handling of the Tuareg rebellion fired in the air during the inspection, prompting an immediate strengthening of security around the presidential palace.
The Tuaregs have forced the army out of several northern towns in recent months.
A presidential election was due to take place in the country in just under a month.
The government had so far refused to postpone the poll, despite the unrest involving Tuareg-led rebels.
Both the US and France have urged the soldiers and government to resolve their dispute through peaceful means.