No group has claimed responsibility, although al-Shabab militants are likely to be the prime suspects.
At the blast scene, the wreckage of a civilian minibus destroyed by the powerful bomb was in the street, with a pool of blood under the vehicle. "I saw five soldiers being carried onto a pickup truck", some of whom were dead, said eyewitness Abdukadir Moalim.
Ten people mostly civilians on mini-bus were on Sunday killed and more 20 others injured after suicide auto bomb attack near the Ministry of Defense in the capital Mogadishu, SONNA reported.
At least 15 people, including soldiers and civilians, were killed and more than five others wounded after a suicide auto bomb blast targeted Somalia's new armed forces commander Sunday.
Abdullah Sanboushli was appointed director of national security and intelligence, Ahmed Aarfish was appointed army commander, Abdullah Aanoud was appointed chief of staff and Abdul Hakim Saeed was appointed chief of police.
The Somali-American president gave al-Shabab members a 60-day amnesty period to surrender and join the government side.
The attack happened in Golweyn village, controlled by Al Qaeda-linked al Shabaab, 110 km (70 miles) to south west of the capital, Mogadishu. Targets have included hotels, military checkpoints and the presidential palace.
"We want to pardon the Somali youth who were misled by al-Shabab", he said.
Al-Shabab is just one of the challenges facing the new government, which despite hundreds of millions of dollars of support from the global community still struggles to expand its authority beyond the capital and other selected areas.