Insurgents ambushed African Union peacekeepers Wednesday who were sent to help stabilize Somalia's violent capital, setting off a gunfight that wounded three civilians, witnesses said. It was the first direct attack on the AU peacekeepers since they arrived Tuesday, the first peacekeepers to enter the capital in more than a decade. Insurgents fired mortars during their welcoming ceremony at Mogadishu International Airport, wounding one civilian. On Wednesday night, gunmen fired on the passing troops from Uganda. "Convoys of Ugandan troops were ambushed as they were passing the main junction in Mogadishu, and they exchanged heavy gunfire with the insurgents," Shino Abdukadir, an eyewitness said. He saw three civilians wounded in the crossfire. Somalia's Deputy Defense Minister Salad Ali Jelle said the Ugandans suffered no casualties. A Ugandan military spokesman was not immediately available for comment. About 800 AU peacekeepers from Uganda have arrived in Mogadishu, and about 200 more are expected. Several other African countries have promised troops, but no date has been set for their arrival. The surge of violence is the latest example of the volatility peacekeepers face in a country that has seen little more than anarchy for more than a decade. The government, backed by Ethiopian troops, toppled a radical Islamic militia here only in late December, and is struggling to keep control. Insurgents believed to be the remnants of Somalia's Council of Islamic Courts have staged almost daily attacks against the government, its armed forces or the Ethiopian military. In Nairobi, Somalia's ambassador to Kenya said a long-discussed peace conference would be held in mid-April. "The preparatory work of the National Reconciliation Congress has started," Mohammed Ali Nor said. He added that it would be led by a committee independent from the government and that 3,000 former politicians, clan elders, religious leaders and business people will participate. However, he said remnants of the Islamic courts who do not renounce violence would not be allowed to participate. The Ugandan troops are the vanguard of a larger force authorized by the United Nations to help the government assert its authority in one of the most violent and gun-infested cities in the world. The force also is meant to allow the Ethiopian soldiers, who came to Somalia in December to support the government, to leave.