Mali's President Ibrahim Boubacar Keïta has been arrested by mutinying soldiers, a government spokesman has confirmed to the BBC.
Prime Minister Boubou Cissé has also been arrested, despite earlier appeals for "brotherly dialogue".
The apparent coup attempt in the West African nation began with gunfire at a key military camp near the capital, Bamako, on Tuesday morning.
In the city young men set a government-owned building on fire.
The arrest of President Keïta and his prime minister has sparked widespread international condemnation.
It came hours after disgruntled junior officers detained commanders and took control of the Kati camp, about 15km (nine miles) from Bamako.
The unrest coincides with calls for more protests to demand that the president resign.
What do we know about the mutiny?
It is led by Col Malick Diaw - deputy head of the Kati camp - and another commander, Gen Sadio Camara, BBC Afrique's Abdoul Ba in Bamako reports.
After taking over the camp, the mutineers marched on the capital, where they were cheered by crowds who had gathered to demand President Keïtas's resignation.
In the afternoon they stormed his residence and arrested the president and his prime minister - who were both there.
The number soldiers taking part in the mutiny is unclear - as are their demands. Some reports say it was fuelled by a pay dispute.
Kati camp was also the focus of a mutiny in 2012 by soldiers angry at the inability of the senior commanders to stop jihadists and Tuareg rebels taking control of northern Mali.
Footage from AFP news agency showed a building owned by the justice ministry in Bamako ablaze on Tuesday.
Analysis by Will Ross, BBC World Service Africa editor
What began as a mutiny appears to have morphed into a coup. This will be welcomed by the huge number of protesters who have been out on the streets for months calling for President Keïta to step down.
Parallels will be drawn between these events and 2012 when the government's mishandling of a rebellion led to another coup.
Violent jihadists took advantage of that chaos to seize northern Mali. And they continue to cause havoc across the region.
Ibrahim Boubacar Keïta won a second term in elections in 2018, but there is widespread anger over corruption, the mismanagement of the economy and the worsening security situation with jihadist and communal violence on the increase.
In recent months huge crowds led by populist imam Mahmoud Dicko have been calling on President Keïta to step down.
Much smaller crowds reportedly gathered in the capital on Tuesday in support of the soldiers.
What has the reaction been?
United Nations Secretary General Antonio Guterres demanded the "unconditional release" of Mali's leaders and the "immediate restoration of constitutional order".
The chairman of the African Union Commission, Moussa Faki Mahamat, said he "emphatically condemns" the arrests of President Keïta and his prime minister.
The Economic Community of West African States (Ecowas) said: "This mutiny comes at a time when, for several months now, Ecowas has been taking initiatives and conducting mediation efforts with all the Malian parties."
Media captionMahmoud Dicko has emerged as the leader of an opposition movement seeking the Malian president's departure
Mali is a key base for French troops fighting Islamist insurgents across the Sahel region, and the former colonial was quick to react to Tuesday's events.
The office of French President Emmanuel Macron "condemned the attempted mutiny under way" and his Foreign Minister Jean Yves Le Drian urged the soldiers to return to barracks
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And today in Africa just gets worse...
