a baby boy was killed and teenage boy beheaded

[Hiiraan boy]

MOGADISHU, March 29 (Reuters) - Helicopters and tanks pounded rebel positions across Mogadishu on Thursday as allied Ethiopian and Somali troops launched a major push to end a bloody insurgency, with at least 11 civilians reported killed.

With scenes of carnage shocking even by Mogadishu standards, residents said the final death-toll could be much higher.

"Patients are coming to us by the minute, it is too much," one harried doctor at Madina hospital told Reuters by telephone.

Several Ethiopian helicopter gunships fired rockets, Reuters witnesses said, in the first use of aerial power in the capital during the increasingly vicious fighting of recent months.

Government and Ethiopian forces are pitted against Islamists ousted from Mogadishu over the New Year and disgruntled clan militia who used to run the lawless capital.

Amid the chaos, one mortar flew into a mosque, killing a baby boy there and beheading another teenage boy.

"My children sought refuge at a mosque when it was hit by a mortar shell. My son died and my daughter lost the toes on one of her feet," local police officer Hashim Hussein told Reuters, his voice cracking with emotion.

Another mortar hit a fuel tank, sparking a huge blaze that engulfed a local watchman and truck owner, witnesses said.

Breaking a rocky ceasefire in place since the weekend, the Ethiopian and Somali government soldiers launched attacks from early morning on insurgents' strongholds in the Ramadan area of north Mogadishu, around the main soccer stadium, and elsewhere.

"I have not seen anything like this," said one terrified inhabitant, Hussein Haji. "Whenever the Ethiopians fire their big guns, all my windows and doors are shaking."

Explosions and gunfire rattled around the streets from soon after dawn, sending residents running for cover in their homes.

"Early in the morning, the government troops and Ethiopians attacked us," said one Islamist source involved in the fighting.

The local Shabelle broadcaster said at least 11 people, mainly civilians, had been killed by stray bullets on Thursday.

It also reported two tanks had been destroyed.

"The Ethiopian forces, who are now facing strong resistance, continue to shell," it added. "Two helicopter gunships started bombardments in the rebel positions of the capital."

TRUCE OVER

Reuters cameraman Farah Roble and reporter Sahal Abdulle, who could not leave their buildings due to the fighting, saw helicopters firing and smoke rising from buildings as explosions and gunfire reverberated around the coastal city.

The Ethiopians had brokered a truce at the weekend with the city's dominant Hawiye clan after a week that saw at least two dozen people killed, soldiers' bodies dragged in streets, and a plane crash probably due to a missile.

That fighting was the worst since the war over the New Year to kick out the Islamists and put President Abdullahi Yusuf's interim government in the capital.

The government represents the 14th attempt at restoring central rule since the 1991 ouster of a military dictator.

The African Union (AU) has sent 1,200 Ugandan troops to help pacify Somalia. But they have also been the target of attacks in the lawless Horn of Africa nation that defied a U.N.-U.S. peacekeeping mission in the early 1990s.

Other African nations are baulking at sending further troops needed to bring the AU force up to its intended total of 8,000.

The United Nations said on Thursday that 57,000 people had fled Mogadishu since February, including 12,000 in the last week. "They are hungry and face harassment from thugs," the U.N. refugee agency said in a statement.