At least four civilians were killed on Wednesday as thousands fled the Somali capital, fearing the conflict could escalate between government forces and Islamist rebels.

Residents said several bombs struck one of the city’s crowded markets.

[Fadumo Kulaneh, Mogadishu Resident]:
"I was there when the mortar hit. There was a crowd of people hiding from the mortars. After the mortar hit, I saw some of them dead and others were wounded. I was not able to differentiate between the dead and the wounded because there were many people in the market."

Islamist insurgents also launched bombs at the presidential palace, prompting government troops to respond with heavy artillery.

The rebels belong to the al-Shabaab group. And the U.S. government says the group is linked to al-Qaeda.

Since 2007, violence has killed thousands and driven more than a million people from their homes. The situation is one of the world's worst humanitarian crisis.

Western security agencies say Somalia has become a safe haven for militants.