Somali state media says the security forces have thwarted an attack on a military base at the sprawling international airport complex outside the capital, Mogadishu.
It says two jihadists were killed as they tried to force their way in.
A column of smoke can be seen rising from the area which hosts international peacekeepers, the offices of UN organisations and diplomatic missions as well as hotels.
No flights are reported to be taking off.
The Islamist group al-Shabab said its militants had attacked the biggest foreign military base in Somalia.
Attacks by al-Shabab have become more frequent while voting has been taking place in much-delayed parliamentary elections.