Shots have been heard near the presidential palace in Burkina Faso's capital amid a mutiny by soldiers.
Gunfire has also been heard at several barracks in Ouagadougou, with soldiers demanding the sacking of military chiefs, and more resources to fight militant Islamists.
Hundreds of people came out in support of the troops, forcing authorities to introduce a night-time curfew.
The government said the crisis had been contained.
It dismissed rumours of a new coup attempt, just over a week after 11 soldiers were detained for allegedly plotting a coup.
The location of President Roch Kaboré is unclear, but the defence minister denied rumours circulating on social media that he was under arrest.
It is the latest sign of growing discontent with President Kaboré's government over its failure to quell the Islamist insurgency that has devastated the West African state since 2015.
Protesters in support of the soldiers set fire to the ruling party's headquarters.
Gunshots were heard at military camps in the west and south of the capital, and at an air base near the main airport.
Soldiers convicted of a coup attempt in 2015 are imprisoned at the camp in the west, known as Sangoule Lamizana.
Shooting was also heard at military bases in the northern towns of Kaya and Ouahigouya, the US embassy said.
The mutineers made several demands, including:
- the dismissal of the army chief of staff and the head of the intelligence service
- the deployment of more troops to the front line to fight the insurgents
- better care for wounded solders, and the families of those killed in battle.
In a televised address to the nation earlier, Defence Minister Barthélémy Simporé said there were "localised, limited" incidents "in a few barracks", and none of the "republican institutions" had been targeted.
Gen Simporé urged people to continue with their normal activities, saying the government would release further information in due course.
Internet monitoring group NetBlocks said that access to the web had been disrupted.
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The killing of 53 people by suspected jihadists in November heightened public outrage against the government, and raised fears that the military would take power – just as it had in neighbouring Mali in May.
On Saturday, dozens of people were arrested in Ouagadougou for holding a banned rally to protest against what they described as the government's inability to deal with the militants.
Mr Kaboré, a former banker and prime minister, became president after winning elections in 2015.
The polls were the first since long-serving ruler Blaise Compaoré went into exile a year earlier following a popular uprising against his rule.