Rebel troops have appeared on Malian state TV to announce they have seized control of the country, hours after attacking the presidential palace.
The soldiers said a nationwide curfew was in force and that the constitution had been suspended.
The troops, who staged a mutiny on Wednesday, say the government is not giving them enough arms to tackle a rebellion by ethnic Tuaregs.
West African regional body Ecowas has condemned the actions of the troops.
In a statement, it said it had followed the situation with "dismay and mounting concern", describing the behaviour of the mutinous soldiers as "reprehensible" and "misguided".
It comes after the renegade troops had staged a mutiny traded gunfire with soldiers loyal to the government.
A source told the BBC that the foreign minister and a number of other ministers have been arrested.
On Wednesday the mutineers had taken 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, with a caption identifying them as the "Committee for the Re-establishment of Democracy and the Restoration of the State".
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.
A spokesman for the renegade soldiers, identified on screen as Lt Amadou Konare, said they had ended the "incompetent regime" of President Amadou Toumani Toure.
Lt Konare condemned the "inability" of the government to "fight terrorism", and said the soldiers would look to hand over to a democratically elected government.
There has not yet been any reaction from President Toure to the announcement.
The BBC's Martin Vogl, in Bamako, said the exact whereabouts of the President Toure were not known.
However, a loyalist military source close to the president told the AFP news agency on Thursday morning that he was well and in a safe location.
Our correspondent said it was not clear whether the mutinous soldiers, up to 15 of whom were seen on screen, have complete control of the presidential palace or have the support of all the Malian forces.
He said an elite force, known as the Red Berets, could still be loyal to President Toure.
He said Mali has had democratic rule for the last 20 years, during which it has come to be seen as a model which other emerging democracies can look to.
'Recruits riot in the north'
The Kenyan government said its foreign minister, Moses Wetangula, and three officials accompanying him are safe in their Bamako hotel after being stranded in Mali.
They were in the country to attend an African Union meeting.
The unrest began on Wednesday as the country's defence minister started a tour of military barracks north of the capital.
Soldiers fired in the air during the inspection, prompting an immediate strengthening of security around the presidential palace.
Troops are upset with the government's handling of a Tuareg rebellion in the north of the country, and are also reportedly opposed to any potential talks with the rebels.
There was heavy gunfire in Bamako throughout Wednesday, and armoured vehicles had moved in to protect the presidential palace. Gunshots reportedly continued to ring out overnight.
A member of the presidential guard described the fighting to AFP.
"We are in control of the presidential palace. People are shooting towards us and we are returning fire," he said.
In the northern town of Gao, young recruits were said to have begun rioting at a military base, according to the Associated Press news agency.
Both the US and France have urged the soldiers and government to resolve their dispute through peaceful means.
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.