MOGADISHU (Reuters) - Artillery shelling between Islamist rebels and Somali government forces killed at least 14 people and wounded 28 others in Mogadishu on Sunday, residents and a rights group said.

Insurgents fired mortars at government troops, prompting a heavier response of shells that killed civilians in several suburbs of Mogadishu and made residents cower indoors.

"Fourteen civilians died and 28 others were wounded on Saturday night and Sunday morning in mortar shell exchanges in Mogadishu," Ali Yasin Gedi, vice chairman of Mogadishu's Elman Peace and Human Rights Organization, told Reuters.

"Most of these people died this morning after an exchange of heavy shelling," he said.

Maryan Said, a resident in the sprawling Bakara market, told Reuters by telephone that six people from one family were killed by one shell that also killed three others in a nearby house.

"Their house has partially demolished and the dead bodies are in pool of blood," she said.

Bakara, which is notorious for its open-air weapons bazaar, has long been viewed by the government and the African Union force AMISOM as a stronghold of hardline Islamist al Shabaab insurgents who are trying to overthrow the country's transitional administration.

Washington accuses the rebel group of being al Qaeda's proxy in the failed Horn of Africa state.