Heavy fighting convulsed the Somali capital Mogadishu on Thursday, killing at least 16 people and wounding nearly 50, hospital sources and residents said, according to dpa. In the ceaseless spiral of violence which has forced hundreds of thousands of residents to flee, gun battles raged overnight Wednesday with mortar shelling punctuating the morning hours in the main Bakara market. Witnesses said it was the fiercest fighting since October. "The shell landed in a crowd of people where a business transaction was going on," said Abdirahman Bile. "Inside the store blood and pieces of flesh were scattered on the ground," added witness Ali Mohamed Gutale. Mortar shells ripped through the busy market sending dozens of injured people to hospital. "We are very overwhelmed treating civilian casualties. Up to 45 injured people were admitted to hospital with 22 in critical condition. Two others died on the surgical bed. They all had serious shrapnel wounds," said Medina Hospital doctor Hassan Osman Burane. Bullet-scarred Mogadishu has been engulfed in vicious fighting between government troops and insurgents that has emptied the city or else forced residents to live in hiding. At least 1,000 people have been killed but a local human rights group puts the number as high as 6,000. The United Nations has warned that sexual violence against women is increasing in the ongoing clashes that began when Ethiopian-backed government forces swooped into the capital at the New Year, ousting a popular Islamist group. Some 600,000 people have poured out of Mogadishu since then, with many setting up makeshift homes on a 30-kilometre stretch of road outside the capital. Civil war broke out in Somalia after the 1991 toppling of dictator Mohammed Siad Barre, which plunged the Horn of Africa country into anarchy.