Yemenis inspect the site of a suicide car bombing claimed by the Islamic State group on August 29, 2016 at an army recruitment centre in the southern Yemeni city of Aden. (Xinhua/AFP Photo)

ADEN, Yemen, Sept. 4 (Xinhua) -- An explosion struck a police checkpoint in Yemen's southern port city of Aden on Sunday, killing six soldiers and injuring at least five others, a government official told Xinhua.

Unidentified attackers detonated a roadside bomb at the checkpoint in Sheikh Othman district of Aden province, causing huge blast that rocked the area, the Aden-based government source said on condition of anonymity.

"The roadside bombing resulted in the killing of six pro-government soldiers who were positioned in the area with their armored vehicles," the source said.

Witnesses confirmed to Xinhua that heavy gunfire took place after the explosion and several ambulances rushed to rescue injured people.

No group has yet claimed responsibility for Sunday's roadside bombing that struck Aden province, where the Saudi-backed government has temporarily based itself.

However, the Yemen-based al-Qaida offshoot and the Islamic State (IS) group used to launch similar suicide bombings against Yemeni army and security forces in the past weeks.

Last month, the IS claimed responsibility for a deadly suicide bombing that struck an army recruiting center in Aden province, leaving about 75 dead and more than 100 injured.

Yemen, an impoverished Arab country, has been gripped by one of the most active regional al-Qaida insurgencies in the Middle East and the affiliate of the IS.

The fragile security situation in the country has deteriorated since March 2015 when war broke out between the Shiite Houthi group, supported by former President Ali Abdullah Saleh, and the government backed by a Saudi-led Arab coalition.

More than 6,400 people have been killed in ground battles and airstrikes since then, half of them civilians.