Iran-backed Houthi forces in Yemen launched a major wave of drone and missile attacks against four cities in Saudi Arabia.

The strikes targeted military sites and several oil facilities, including an Aramco refinery in Jizan, causing fires and damage.

Saudi authorities said 73 people, including women and children, were wounded in the attacks.

Saudi Arabia vowed to retaliate, raising fears that the fighting could further escalate after years of relative calm in the Yemen conflict, The Guardian has reported.

The attacks also threaten global energy supplies and pushed oil prices closer to $100 a barrel as the wider war involving Iran, the U.S. and Israel continues.