There has been heavy gunfire at the international airport in Kinshasa, the capital of Democratic Republic of Congo, a customs official has told Reuters.
It came minutes after witnesses reported gunmen attacking the headquarters of its state radio and television.
The official told Reuters: "Shooting has started here. They are shooting everywhere. We are all hiding."
Several people have been taken hostage by armed youths at state television headquarters in the capital of Democratic Republic of Congo, according to AFP.
Before the station's television feed was shut down, two presenters were seen on screen, under threat from a young man standing behind them.
Police spokesman colonel Mwana Mputu told the news agency: "They are armed with machetes and guns. They have taken reporters hostage. An operation is under way to dislodge them,"
Witnesses have reported hearing heavy gunfire at the headquarters of Democratic Republic of Congo's state radio and television station.
Both channels were off air after the shooting was heard.
State television journalists at the site said the Congolese army had launched an attack on the building to dislodge unidentified assailants.
The International Criminal Court has acquitted the Congolese warlord Ngudjolo Chui of all charges of war crimes and crimes against humanity.
Ngudjolo had been accused by prosecutors of directing militias to kill, pillage and rape during a conflict in the northeastern Ituri province of Congo in 2003.
Presiding judge Bruno Cotte said atrocities had been committed during the conflict but prosecutors had failed to tie them to Ngudjolo.
Heads of state from Africa's Great Lakes region have called on the M23 rebel group in the Democratic Republic of Congo to end their campaign and leave the town of Goma which they captured this week.
A joint statement from the leaders after their meeting in Uganda urged the M23 to end attempts to overthrow the elected government and to "stop all war activities and withdraw from Goma".
Democratic Republic of Congo president Joseph Kabila is meeting with other regional leaders in Kampala to try and end the crisis in his country, a Uganda government spokesman has told Reuters.
The UN has warned of a growing humanitarian crisis in DRC after rebels continued their advance towards capital Kinshasa.
The head of the political arm of the M23 rebel group which took control of the eastern city of Goma this week is also in Kampala, but it was not clear whether he would hold direct talks with Kabila.
The United Nations Security Council has condemned the capture of Goma in the Democratic Republic of Congo by M23 rebels.
A statement by the 15-member council said: "(The council) demands the immediate withdrawal of the M23 from Goma, the cessation of any further advances by the M23 and that its members immediately and permanently disband and lay down their arms."
UN experts claim Rwanda is behind the rebellion in eastern Congo and that Uganda has also aided M23.
Both countries deny the accusations.
The Congolese M23 rebels, who UN experts claim are backed by Rwanda, have reached the outskirts of Goma but claimed they do not plan to take the city.
The group claims they are within two miles of the city which is home to the headquarters of the UN peacekeeping mission in eastern Democratic Republic of Congo.
Rebels in eastern Democratic Republic of Congo have advanced to within two miles of the largest city in the area, Goma.
The M23 rebels captured Kibumba, a town 19 miles north of Goma, on Saturday and claim they can "easily" take the city.
Col. Vianney Kazarama, a spokesman for the rebels, said: "We can take Goma easily now, we have pushed the Congolese army back over 10 kilometers (six miles) in one day. We are confident that we can take Goma and then our next step will be to take Bukavu".