"The last one just landed a few minutes ago," one resident of Kadugli told AFP.
Rebels of the Sudan People's Liberation Army-North (SPLA-N), fighting since 2011 in South Kordofan, have periodically shelled Kadugli since late last year, causing some fatalities.
Neither the SPLA-N nor Sudan's military could be immediately reached for comment.
"I heard about three mortars," a second resident told AFP, adding that two had hit the centre of town near a bus depot.
The other resident also said the town centre had been struck, but he spoke of six shells slamming into the area.
