The death toll from a truck bombing in central Somalia grew to 21, as rescue teams crawled through the wreckage to find additional victims trapped beneath shattered bricks, concrete, and metal.

On Saturday, a suicide bomber drove an explosive-laden truck towards a security checkpoint in the town of Beledweyne, sparking an explosion that burned neighboring buildings, trapped inhabitants, and injured others.

Somali Deputy Health Minister Mohamed Hassan announced Saturday that 13 severely injured people were evacuated and moved to Mogadishu for intensive care.

Ahmed Yare Adan, a local police officer, told AFP that the death toll went up from 13 to 21 after dead bodies were uncovered from beneath destroyed buildings. Some, he noted were "burnt beyond recognition."

Read more: More than 100 al Shabaab terrorists killed in military operation

He added that people were still in search of their family members, unaware if they had survived or not.

Deputy commander of the Beledweyne police station, Sayid Ali, told AFP that a busy neighborhood housing residential buildings and businesses was targeted.

"The search and clearing operation is going on at the site of the explosion," Ali remarked.

The Somalian President Hassan Sheikh Mohamud vowed to eliminate al Shabaab militants following the attack, adding that incidents like yesterday's will not deter the Somalian government from eliminating them.

No group claimed responsibility for the attack; however, al Shabaab, which was forced out of Mogadishu in 2011 still controls large swaths of the countryside.

ATMIS condemns the attack 

An African Union force was sent to Somalia in 2007 with a six-month mission but is still present.

The head of ATMIS, Mohamed El-Amine Souef criticized Saturday's explosion, saying it was "a heinous attack on innocent civilians intended to divert attention" away from the losses incurred by al Shabaab as a result of Mogadishu's onslaught last year.

Last year, Somalia's President Hassan Sheikh Mohamud launched an "all-out war" against al Shabaab, which retains power in large swathes of rural areas and continues to carry out attacks against security and civilian targets, including in the capital, Mogadishu.

However, Somalia's national security adviser recently requested a 90-day extension in the scheduled withdrawal of 3,000 ATMIS personnel by the end of September in a letter to the United Nations.

The request, obtained by AFP, explained that the government "managed to re-liberate towns, villages, and critical supply routes" during its onslaught but had suffered "several significant setbacks" since late August.

In early September, more than 30 Al-Qaeda-linked al Shabaab terrorists were killed while attempting an attack in the Qoryoley district in the Lower Shabelle region, during an operation carried out by the Somali Armed Forces and their international partners, state-run Somali news agency SONNA reported on Saturday.