Three weeks of fighting across Yemen may be pushing a country where Sunnis and Shi'ites have prayed in the same mosques for centuries toward a sectarian war, Reuters reported.
Most combatants deny they are motivated by religion in the conflict. Iran-allied Shi'ite Houthi rebels say they are leading a just revolution and Sunni Muslim Saudi Arabia contends it has been bombing the Houthis to protect the Yemeni state.
Militiamen from the south cite defence of their homeland.
But there are signs that the sectarian hatred that has engulfed the Middle East since the Arab Spring uprisings of 2011 is creeping into Yemen's war, fueled by a rivalry between regional powers Saudi Arabia and Iran.
Conflict and power struggles are not new to Yemen, one of the most heavily armed societies in the world. But the sectarian trend was captured on a video shared by Yemeni Facebook users.
A teenager sits blindfolded and cries, pleading to his captors that he is only 13. He was detained by militiamen while fighting for the Houthis in the southern city of Aden.
"Why did you come here?" a Sunni gunman shouts. "We're here to defend our religion in jihad against the apostates and Houthis...you're not people, you're animals!"
After nearly three weeks of airstrikes by Saudi Arabia and its Sunni Gulf neighbours who see the Houthis as Iranian puppets, Yemen risks being carved up along religious lines.
"This scenario is likely if the war goes on. If young men continue to die, towns are invaded and homes shelled, the appeal of extremist religious groups will only grow," Mahmoud al-Salmi, a history professor at Aden University said.
Houthis have been fighting what they call marginalisation by the state for over a decade. But the militia is now also motivated by a desire to eliminate the hardline Sunni al Qaeda from Yemen.
As the chaos spreads, there is a danger that all sides will exploit their religious beliefs while settling old scores.
The formerly independent and socialist South has long felt aggrieved by the North, not because it is home to the Zaydi sect of Shi'ite Islam, but because Southerners felt shut out of politics and oil resources that benefited northerners.
"There's a strong feeling of oppression and humiliation that Northerners are invading. But since there's no leadership and no army, the armed groups lack discipline and this anger on regional lines could turn sectarian," al-Salmi said.