Assailants armed with heavy weapons attacked the presidential palace and the residence of the Central African Republic's embattled leader, but were pushed back.
Guy Simplice, spokesman for president Michel Djotodia, said there had been heavy fighting late last night near the seat of government in the capital Bangui, before the army was able to block the aggressors.
Although the attackers could not immediately be identified, there have been rumours that a Christian militia, believed to be backed by the president ousted by Mr Djotodia in a coup nine months ago, would attempt to seize back power.
The heavy arms fire could be heard from the five-star Hotel Ledger, near the centre of town, where international journalists are staying.
A rocket came over the hotel's wall, landing on the hotel grounds. As the shooting died down, helicopters could be heard flying overhead.
The events are the latest indication that the deeply poor, but until recently relatively stable nation, is tipping into anarchy.
Earlier yesterday, international forces were sent to pick up truckloads of decomposing bodies of dead Muslims, whose remains had been left at a local mosque by their friends and relatives.
They were too frightened to be seen burying them in a city where Christian-on-Muslim and Muslim-on-Christian attacks have become a daily occurrence.
It also comes a day after the African Union lost six peacekeepers, who were attacked in the Gobongo area of the capital.
Their destroyed car, with at least one body still inside, had not been removed a day later, showing how dangerous the country has become, even for the international forces tasked with pacifying it, said African Union spokesman Eloi Yao.
As the African Union was struggling to secure that crime scene, they discovered another: Close to the presidential palace, peacekeepers discovered a mass grave.
"We found around 20 bodies in a state of decomposition in an area that we call Panthers' Hill. The 20 were scattered in different graves in a small area. You found five bodies in one hole, three in another, two in yet another and so on," Mr Yao said.
UN Secretary-General Ban Ki-moon said he is "appalled" by the continuing violence, including reports yesterday of dozens more bodies found on the streets of Bangui.
He called on the authorities "to rein in those fomenting and perpetrating the violence," UN spokesman Martin Nesirky said.
The UN chief welcomed appeals for peace by Christian and Muslim leaders, reiterated that those responsible for atrocities must be held accountable, and expressed sadness at the deaths of the six peacekeepers and a UN national staff member, Mr Nesirky said.
The Central African Republic has been plunged into chaos, as the country's Christian majority seeks revenge against the Muslim rebels who seized power in a coup in March.
Both Christian and Muslim civilians are now armed, and the foreign troops brought in to try to rein in the violence have been sucked into the conflict, accused of taking sides.
The Chadians, part of an African Union force, are Muslim and are seen by the population as backing the Seleka rebels who toppled the nation's Christian president in March.
However the 1,600 French troops who were deployed here in the first week of December are accused of backing the Christian majority, and their patrols have come under fire in Muslim neighbourhoods.
The UN estimates that 639,000 people out of a population of 4.5 million have been forced to flee their homes. Altogether two million people need humanitarian aid - almost half the country.