Press TV reports.
Senior al-Shabab official Sheikh Adil Mohamed told Press TV that the unmanned aerial vehicle dropped missiles on the outskirts of Afmadow, which is on the border with Kenya.
Somali Transitional Federal Government military officer Cali Jimcale said the drone attack was launched from a base in Kenya.
Somalia has not had an effective central government since 1991, when warlords overthrew former dictator Mohamed Siad Barre.
The weak Western-backed transitional government in Mogadishu has been battling al-Shabab fighters for the past five years and is propped up by a 10,000-strong African Union force from Uganda, Burundi, and Djibouti.
Nine al-Shabab fighters have been killed and dozens of others injured in an attack by a US assassination drone in southern Somalia,