Unknown gunmen opened fire and killed a senior cleric of the Muslim Salafist Movement near a mosque in Yemen’s southern port city of Aden on Saturday, a security official told Xinhua.

“Masked gunmen used silenced weapons and killed Sheikh Adel Shehri, Imam of a mosque in Aden’s neighborhood of Enma, before fleeing to unknown location with a speeding car,” the official said on condition of anonymity.

He added that the well-known cleric died immediately at the scene after receiving six bullets while he was heading to perform morning prayers in a nearby mosque.

According to security sources, similar three drive-by shootings occurred earlier this month and targeted Muslim clerics loyal to the Southern Transitional Council backed by the United Arab Emirates.

Residents said that large number of UAE-backed Yemeni security forces were deployed in and around the entrances of Enma neighborhood and started tracking suspected elements there.

No one has claimed responsibility for the attack so far, but Yemeni security officials accused gunmen linked to the Islamic State terrorist group of being behind such drive-by shootings in Aden.

Militants of the Yemen-based al-Qaida branch and the Islamic State group (IS) are more active in the country’s southern part and Yemeni armed forces supported by the UAE started waging large offensives against some hideouts there.

The al-Qaida and Islamic State-linked terrorists took advantage of the security vacuum and ongoing civil war to expand their influence and seize more territories in Yemen.

Security in Yemen has further deteriorated since March 2015, when war broke out between the Shiite Houthi group, supported by former President Ali Abdullah Saleh, and government forces backed by a Saudi-led Arab coalition.

UN statistics show more than 10,000 people, most of them civilians, have been killed since the coalition intervened in the Yemeni civil war that also displaced around three million.

The impoverished Arab country is also suffering the world’s largest cholera epidemic since April, with about 5,000 cases reported every day.