MOGADISHU, Somalia – Mortar rounds slammed into a market in Somalia's capital on Monday, killing at least 17 people, after a failed insurgent attack on the presidential palace.

Also Monday, a remote-controlled land mine killed a Somali driver and wounded two aid workers – an Italian and a Somali – some 60 miles southwest of Mogadishu. The aid workers' injuries were not critical, Dr. Abdi Rahman said.

Witnesses said those killed in the capital included a 13-year-old. The fighting began when insurgents fired mortars at the presidential palace but missed, according to military spokesman Dahir Hersi.

Al-Shabab, a radical Islamic group at the heart of the Somali insurgency, claimed responsibility for the initial attack.

Mortar shells then slammed into the Bakara Market, where people can buy everything from packets of rice and sugar to grenades and AK-47s. The government suspects insurgents use the market as a base and it often comes under fire.

Twenty-four humanitarian workers have been killed in Somalia this year. On Monday, 52 aid groups issued a joint statement calling for international help for the devastated people.

“The international community has completely failed Somali civilians,” the statement said. It appealed to the warring sides to allow aid workers unhindered access to all parts of Somalia.

“The poorest of Mogadishu's residents have no means to flee the extreme violence and have limited means to earn a living, leaving them completely dependent on humanitarian assistance,” the statement said.

Somalia is among the world's most violent and impoverished countries. The nation of some 8 million people has not had a functioning government since warlords overthrew a dictator in 1991 then turned on each other.

A quarter of Somali children die before age 5; nearly every public institution has collapsed. Fighting is a daily occurrence, with violent deaths reported nearly every day.

Islamic militants with ties to al-Qaeda have been battling the government and its Ethiopian allies since their combined forces pushed the Islamists from the capital in December 2006. Within weeks of being driven out, the Islamists launched an insurgency that has killed thousands of civilians.

In recent months, the militants appear to be gaining strength. The group has taken over the port of Kismayo, Somalia's third-largest city, and dismantled pro-government roadblocks. They also effectively closed the Mogadishu airport by threatening to attack any plane using it.

Elizabeth Kennedy reported from Nairobi, Kenya.