At least 13 people were killed Tuesday in fighting between rebels and African Union peacekeepers in the Somali capital of Mogadishu, said Reuters.

Both sides exchanged machine gun and artillery fire following a rebel attack in the capital. It's described as some of the heaviest fighting in the city in weeks.

Witnesses said a mother and child died when a shell landed on their home, while at least 11 other civilians were killed, said the report.

Officials at a local hospital said at least 45 people have been injured.

The rebels have vowed to continue attacks on the roughly 3,400 African Union troops in the country, said Reuters.

Rebels killed 11 AU peacekeepers during an attack on Sunday.

Somalia, a nation of about eight million people, has not had a functioning government since warlords overthrew a dictator in 1991 and then turned on each other.

Islamic militants with ties to al-Qaeda have been battling the shaky transitional government and its Ethiopian allies since their combined forces pushed the Islamists from the capital in December 2006.

Violence in the country has killed roughly 160,000 civilians during the past two years. More than one million people have been forced from their homes.