A roadside bomb explosion hit a passenger bus in Yemen's southeastern province of Hadramout on Thursday, leaving four people killed.

Axar.az reports citing Xinhua.

The Yemeni security official, who spoke on condition of anonymity, said that the roadside blast struck the civilian bus while it was traveling near the Saudi-Yemeni border post of Wadia in Hadramout province.

"An explosive device hit a traveling bus carrying 46 passengers near the Wadia crossing, killing four passengers and injuring 21 others, six of them seriously," the source added.

The Improvised Explosive Device (IED) was apparently planted to target a military convoy of the Saudi Arabia-led coalition that passed later through the same road, according to the official.

Earlier in the day, a roadside bomb blast struck a military patrol of the Saudi-led coalition forces in the historic town of Shibam in Hadramout province that's controlled by Yemeni government forces.

A Yemeni official based in Hadramout confirmed to Xinhua that the blast killed a Saudi army commander named as Abu Nawaf along with five of his bodyguards.

No one immediately claimed responsibility for the attacks in Hadramout. But militants of the Yemen-based al-Qaida branch are active in the region and often use roadside bombs to target government officials as well as Yemeni security forces.

The Yemeni government-controlled provinces, including Hadramout, are witnessing growing activities of extremist organizations that take advantage of the ongoing conflict in the impoverished Arab country.