Thickly bearded men — some wrapped in traditional outfits, others masked — can be seen these days driving through Yemen’s central city of Taiz in pickup trucks mounted with machine guns.

The men belong to a growing faction of Salafis, an ultra-conservative Sunni religious group. In Taiz, the Salafis were once known for being preachers in mosques and religious scholars, but now they have become the most dominant fighters among local resistance to the Shiite Houthi rebels, who ousted from power Yemen’s President Abdu Rabbu Mansour Hadi.

First seen in March of last year, when forces loyal to the Houthis swept into the city, the Salafi fighters have increased in number since the Saudi-led coalition began its air campaign. Their presence in Taiz, the third-largest city in Yemen, has been particularly notable.

Residents worry that the growing Salafi movement is laying the groundwork for even more conflict among religious groups. According to several local residents, Homat al-Aqida fighters, the largest of five Salafi factions in Taiz, resemble al Qaeda-linked groups.

Some residents “see the Salafis as synonymous to al Qaeda,” said Mohammed al-Azaazi, a Taiz university student. “The Salafis have detained several people and carried out public executions, while claiming they apply the Islamic Sharia.”

While the Salafi factions in Taiz deny they have links to al Qaeda, their fighters spearheaded the attack on the central prison last year, which led to dozens of prisoners escaping, including al Qaeda members.

The Salafi fighters’ presence is still relatively new in Taiz, but is rapidly transforming the city, according to Baleegh al-Zuraiqi, 34, a local resident in downtown Taiz. The Salafis have been based in four neighborhoods since the fighting started, al-Zuraiqi said, “including Bab Mosa, where they have established an Islamic court to solve issues and cases among the local people.”

According to local sources, the Salafis now account for nearly half of the anti-Houthi alliance in Taiz, which consists of thousands of fighters. One member of a Salafi faction in Taiz, who asked to remain anonymous, said his group acquired some weapons from the Saudi-led coalition, but insists they “will return the arms after the war is over in Taiz.”

The member said his faction, which consists of more than 500 recruits, will continue to fight the Houthis until they’re driven out of Taiz. “Then,” he said, “our war will end.”

Yet residents of the city worry that the growing religious factions have permanently altered the city.

“Taiz is no longer ‘the city of dreams,’” said Abdurraqib al-Majeedi, a local poet and writer who left the city for Sanaa, Yemen’s capital, escaping the fierce fighting and the crippling siege. “It has become a city of war — a hub for extremist fighters and militias.”