The attack was not immediately claimed, but eyes are on the al-Shabaab, an al-Qaeda affiliated group that regularly carries out suicide bombings in the poor and volatile Horn of Africa country.
"A suicide bomber drove an explosives-laden vehicle into a guesthouse in Bardera where government officials were staying," said Hussein Adan, a police commander in the town in the Gedo region 450 kilometers west of the capital Mogadishu.
The officials included Gedo governor Ahmed Bulle Gared and several military commanders, he added.
"The explosion destroyed most of the building and five security personnel were killed," Adan said, adding that 11 other people were injured, including the governor, without giving further details on the severity of the injuries.
"We have never heard anything as big as the explosion this morning, it shook the earth like an earthquake," Mohamud Saney, a witness, told AFP.
The al-Shabaab militants have been fighting the internationally-backed federal government since 2007. Driven out of the country's main cities in 2011-2012, they remain firmly entrenched in large rural areas.
President Hassan Sheikh Mohamoud, who returned to power in May 2022, has promised them "total war".
But the al-Shabaab continue to carry out bloody attacks in retaliation, demonstrating their ability to strike at the heart of Somali cities and military installations.
On 29 October 2022, two car bombs exploded in Mogadishu, killing 121 people and injuring 333, the deadliest attack in five years in this country also affected by a historic drought.