Soldiers in Guinea staged an uprising in the capital on Sunday (September 5).
In a broadcast on state television, they claimed to have dissolved the constitution and the West African state's government.
One unidentified soldier, draped in Guinea's national flag, said the group planned to form a transitional government, and that further details would be given later.
Meanwhile, videos appearing to show the country's president, Alpha Conde, being detained by army special forces circulated on social media.
Reuters could not immediately authenticate the footage, but it was posted just hours after heavy gunfire broke out near the presidential palace in Conakry.
Several sources have claimed an elite national army unit led by a former French legionnaire, Mamady Doumbouya, was behind the unrest.
"We have decided after taking the president who is with us now... to dissolve the current constitution... we also decided to dissolve the government, to close the land and air borders. We call on our brothers in arms to unite in order to respond to the legitimate aspirations of the people of Guinea. We also invite everyone to stay in their bases and continue their usual activities, we will not make the same mistakes as in the past."
Right now though, it's not immediately clear who holds power.
The Guinean defense ministry said the attack on the palace by mutinous forces and an attempted insurgency had been put down.
Earlier, videos shared on social media showed military vehicles patrolling Conkary's streets.
One military source said the only bridge connecting the mainland to the Kaloum neighborhood, which houses the palace and most government ministries, had been sealed off.
That source added that many soldiers, some heavily armed, were also posted around the palace.