MOGADISHU, SOMALIA: Hundreds of Somali government troops attacked insurgent-held positions north and south of the capital Friday and the heart of the city was heavily shelled, witnesses said. One said a busload of fleeing civilians was hit.

Shelling was heavy on a major north-south route through the city, Wadnaha Road, which the Islamic fighters took earlier this month, area resident Abdi Haji said. It is one of the four main roads in the capital, Mogadishu.

Friday’s surge in fighting, following a few days’ lull in a strong insurgent advance on Mogadishu, has killed at least 15 people and wounded more than 150, residents, medical officials and an independent radio station said.

Pictures of the fighting showed gunmen crouched behind the ruins of shell-pocked buildings and bodies lying in the streets. In one photo, a man clutches a wounded child to his chest in the back of a car, his shirt reddened with the blood streaming from the child’s face. In another, a man’s lower jaw has been torn away by a bullet or piece of shrapnel.

Editor Abdirahman Yusuf Al-Adala of the independent radio station Shabelle Media Network also said a stray bullet killed journalist Abdirisaq Warsame Mohamed as he headed to work.

The Islamist insurgents are attempting to dislodge the U.N.-backed government from the few blocks of the capital it still controls. But the government is supported by 4,350 African Union peacekeepers, who are helping hold key installations such as the port, the airport and the presidential palace.

Government commander-in-chief Lt. Yusuf Osman Dumal said the fighting Friday began when Islamists attacked government positions. But residents said the government used the temporary respite to reinforce and re-equip the troops under its control and that it appeared to be a planned government offensive.

Defense Minister Mohamed Abdi Gandi said the government launched the attack ”to defend its people and defeat its opponents.”

”We have captured new bases. We have conquered areas controlled by rebel groups,” he said at a news conference in the capital. ”We will continue the offensive against the rebels until we impose our authority all over the country.”

But insurgents said they had repelled the government forces.

”The so-called government has attacked our bases. We have beaten them back and they retreated to their former stations,” a spokesman for the insurgent Islamic Party, Muse Abdi Arale, said.

The United Nations reports that around 49,000 residents have fled the fighting in the capital, and the humanitarian situation is dire. Many families live without access to food or water under trees or by the side of roads, sheltered by nothing more than a few scraps of plastic.