More than 250 people have been killed since the upsurge of fighting began
At least 10 people have been killed and 20 others injured by a mortar bomb blast at a mosque in Mogadishu.
The tragedy came as a UN official said the recent spate of bloodletting in the Somali capital was the "worst ever" in nearly two decades of chaos.
It was unclear who fired the mortar but it came as pro-government forces continued to fight Islamist guerrillas.
More people died when shells fired by government forces and peacekeepers hit Mogadishu's main Bakara market.
The ongoing battles have killed more than 250 people - civilians and combatants - since it erupted last month.
Neither side is thought to have achieved any territorial gain in the latest confrontation.
On Wednesday, Mogadishu's police commander was killed during an attack on insurgent bases.
BBC East Africa correspondent Will Ross says the death of Colonel Ali Said will be a significant setback for the pro-government forces, as he had often been on the frontline encouraging his colleagues to defend their positions.
Dadir Ali Jes, who witnessed Wednesday night's mosque attack, said he believed at least 13 people had died.
Another resident, Halima Gedi, said: "It was a horrific scene, human flesh scattered everywhere and the blood stained the nearby walls. One of the victims had their head cut off by the mortar."
There was further bloodshed when government forces and peacekeepers shelled Mogadishu's Holwadag district and some of the explosives hit the main Bakara market.
"At least five people were killed and 10 others injured, including a 10-year-old child," said Abdi Haji, a shop-keeper at the market.
The shelling came after the insurgents briefly attacked the strategic Makka-al-Mukarama road in the south of Mogadishu, a route used by government officials and the peacekeepers.
More than 120,000 people have been displaced by the recent violence
More than 100 wounded people have been transported to hospital since Wednesday morning, said Ali Muse, of the city ambulance service.
Guillermo Bettocchi, the UN refugee agency's representative to Somalia, told the BBC's Focus on Africa programme: "This latest spate of violence has been already qualified by people who have been following Somalia for the last 20 or so years as the worst violence ever in Mogadishu. For me, Mogadishu today is like hell."
As well as those killed, more than 120,000 people have been displaced in the latest upsurge of violence, the United Nations says.
Meanwhile Unicef, the UN children's agency, says Islamist fighters have looted its supplies being held in the southern Somali town of Jowhar.
Somalia has not had an effective national government since 1991 and some four million people - a third of the population - need food aid, aid agencies say.