Yemen’s Iran-backed Houthis killed at least 58 government troops in missile and drone attacks on Thursday, a military source said, and wounded 11 civilians inside Saudi Arabia itself, in one of the deadliest days of Yemen’s civil war in four years.

Axar.az reports, citing The Times of Israel, that the attacks come as Yemen is increasingly drawn into the US-Israeli war with Iran, with the rebels stepping up attacks against both government forces and neighboring Saudi Arabia, a key US ally and supporter of the internationally recognized Yemeni government.

Houthi military spokesman Yahya Saree said the rebels attacked government positions with ballistic missiles and drones in response to an alleged military buildup backed by neighboring Saudi Arabia.

The attacks killed at least 58 government troops and injured dozens, according to the military source who spoke on condition of anonymity. Medical sources had earlier spoken of 38 dead.

It should be noted that 30 Yemeni government troops were killed a day earlier in Houthi missile strikes on military camps in the provinces of Marib and Hadramawt.