"We received 10 bodies, among them children, and 15 wounded people," the medic from Al-Nasr hospital in the southern province of Daleh told AFP.
Witnesses said that an army tank had shelled the tent in Sanah, 300 km south of the Yemeni capital in Daleh province, in an attack linked to tension between southerners and the political and military authorities.
One witness told AFP by telephone that troops fired more shells "when we tried to hospitalize the casualties," adding that "there are wounded victims still inside the tent."
The tent was set up by the Southern Movement, which is campaigning for autonomy or outright secession for the formerly independent south, for mourners paying condolences following the death of a man killed during clashes with security forces on Monday.
The clashes in Daleh erupted when southern secessionists attempted to storm the governorate building to hoist a flag of the former South Yemen, which was an independent state until it was united with the north in 1990.
The gunfight left two Yemeni policemen and a civilian dead.
Violence has intensified in south Yemen amid tribal anger over the killing of a local chief and his bodyguards at a checkpoint earlier this month.