The state-run Somali National Television said on Twitter that security forces were dealing with a "terrorist incident" at the hotel, which al Shabaab terrorist group has taken responsibility for.
"There is a blast at Tawakal hotel and there is gunfire being heard," Mohamed Nur, a police captain, told Reuters from Kismayu.
Details of the casualties and damages of the incident have not yet been reported.
There was no immediate word on casualties.
Witnesses said a huge blast was heard before the gunfire started.
"The security forces have besieged the scene," Farah Ali, a shopkeeper in Kismayu, told Reuters.
Al-Shabaab has repeatedly attacked government troops and African Union peacekeeping forces in Mogadishu, the capital of Somalia, and has carried out several operations in other parts of Africa.
MP/PR