A military armoury in Sierra Leone's capital Freetown came under attack on Sunday, the government announced, as it imposed an immediate national curfew.
The government said those attempting to break into the armoury at a major army barracks had been repelled, but the public were asked to stay at home.
Witnesses told AFP they heard gunshots and explosions in the city's Wilberforce district, where the armoury is located as well as a number of embassies.
Other witnesses said they heard exchanges of fire near a barracks in Murray Town district, home to the navy, as well as outside another military site in Freetown.
Automatic weapons fire and explosions could be heard on soundtracks posted on social networks.
The streets of the capital were empty, the witnesses said.
"The public is assured that the government and our state security forces are in control," Information Minister Chernor Bah wrote in a "public notice".
"To enable the security forces to continue the process of apprehending the suspects, a nationwide curfew is declared with immediate effect across the country," the minister said.
No details were given on the alleged perpetrators of the attack, or their motives.
Sierra Leone, an English-speaking country in West Africa, has been going through a political crisis following presidential and general elections in June this year.
West Africa has seen a series of military coups and attempted coups since August 2020.
Mali, Burkina Faso, Niger and Guinea, which shares a border with Sierra Leone, have all fallen under military control.
Sierra Leone President Julius Maada Bio also offered assurances that calm had been returned to the capital, urging people to stay indoors.
"In the early hours of this morning, there was a breach of security at the Military Barracks at Wilberforce in Freetown, as some unidentified individuals attacked the military armoury," he posted on X, formerly Twitter.
"Unidentified individuals attacked the military armoury. However, they were repelled by our gallant Security Forces and calm has been restored," said Bio.
"As the combined team of our Security Forces continue to route out the remnant of the fleeing renegades, a nationwide curfew has been declared and citizens are encouraged to stay indoors," Bio said.
He added that the government would "continue to protect the peace and security of Sierra Leone against the forces that wish to truncate our much-cherished stability" and said it was "resolute in our determination to protect democracy in Sierra Leone."
Bio, who was first elected in 2018, was re-elected in June with 56.17 percent of the vote -- just over the 55 percent needed to avoid a run-off.
International observers condemned inconsistencies and a lack of transparency in the count, as well as acts of violence and intimidation.
The main opposition All People's Congress (APC) party disputed the results of the presidential, legislative and local elections on June 24 and has boycotted all levels of government.
The APC and the government signed an agreement in October following talks mediated by the Commonwealth, the African Union and the West African bloc ECOWAS.
The APC agreed to end its boycott and begin participating in government in exchange for an end to detentions and court cases it said were politically motivated.
