A bomb blast ripped through a bus carrying members of Yemen's air force to their base in the capital Sanaa, witnesses said. At least 6 people were killed and 26 others injured, officials at the scene told Reuters.

They spoke anonymously as no one has been given authorization to discuss details just yet. Yemeni journalist Mohammed al-Qadhi reports that three of the soldiers are in a critical condition.

An air force officer, Ameen Saree, happened to be nearby and was among the first at the scene. He said a bomb had been planted inside the vehicle. "The bomb exploded in the rear part of the bus and six of our colleagues were immediately killed… the rest have been injured and are being treated in hospitals,”he told Reuters. 

It is not yet clear how many people were on-board the bus, or who might be responsible for planning the attack. However, the government of Yemen is battling with Al-Qaeda and other extremist elements, who often target the armed forces. This is a more common occurrence in the south and east of the country, where lawlessness allows the Islamist insurgency to flourish. 

More than 90 soldiers were killed in May 2012, when a suicide bomber disguised himself as one of them at rehearsals for an army parade in central Sanaa. 

The branch of Al-Qaeda common to the territory is thought to be the most dangerous, according to the United States. A recent security threat has forced it, and other Western countries, to shut their diplomatic missions in Yemen, the wider Middle East and parts of Africa and Asia. 

Yemen is one of the poorest states in the Arab world, while it sits next to Saudi Arabia - the world's largest oil exporter. It has also been going through a period of political upheaval in the two years since the pro-democracy protests against former President Abdullah Saleh broke out. 
 

Forensic experts inspect a bus after a bomb attack in Sanaa August 25, 2013.(Reuters / Khaled Abdullah)

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