The President of Burkina Faso, Roch Kaboré, has reportedly been detained by mutinying soldiers.
Some troops in the West African nation have demanded the sacking of military chiefs and more resources to fight Islamist militants.
Gunfire had been heard overnight near the presidential palace and at barracks in the capital, Ouagadougou.
The government on Sunday denied suggestions of a military coup or that the president was under arrest.
President Kaboré was detained at a military camp by mutinying soldiers, foreign media reports say.
Video from the capital appears to show armoured vehicles - reportedly used by the presidency - peppered with bullet holes and abandoned in the street.
BBC reporter Simon Gongo in Ouagadougou says the city is quiet again. Soldiers have, however, surrounded the state television headquarters and there has been no live programming on Monday.
On Sunday, hundreds of people came out in support of the soldiers and some of them set fire to the ruling party's headquarters. A night-time curfew has since been imposed.
The president's location is unknown, but AFP news agency quoted security sources as saying that he and other government ministers are at the Sangoule Lamizana barracks in the capital.
There has been no communication from President Kaboré himself since Sunday night, when he posted to social media congratulating the national football team on their win in an Africa Cup of Nations match.
Amid disruption to the internet, the situation in the capital is not clear, with no statement from either the military or the government.
The unrest comes a week after 11 soldiers were arrested for allegedly plotting a coup.
But discontent has been growing in Burkina Faso over the government's failure to defeat an Islamist insurgency in the country since 2015.
That escalated to new highs in November, when 53 people, mainly members of the security forces, were killed by suspected jihadists. And on Saturday, a banned rally to protest against the government's perceived failure led to dozens of arrests.
Similar troubles in neighbouring Mali led to a military coup in May 2021 - one that was broadly welcomed by the public.
In Burkina Faso, mutinying soldiers made several demands, including the removal of the army's chief of staff and the head of the intelligence service; more troops to be deployed to the front line; and better conditions for the wounded and soldiers' families.
On Sunday, Defence Minister Gen Barthelemy Simpore downplayed previous rumours of the president's capture, and the nature of the unrest at large.
State television, meanwhile, had characterised the sound of gunfire at military barracks as the actions of a small few disgruntled soldiers rather than a widespread fight or coup attempt.