U.S. Marines opened fire on demonstrators during the storming of the Karachi consulate over the weekend, two U.S. officials said on Monday—a rare use ​of force at a diplomatic post that could sharply escalate tensions in the country ‌amid widespread protests over the killing of Iran’s leader.

Ten people were killed on Sunday when protesters breached the compound’s outer wall after Iranian Supreme Leader Ayatollah Ali Khamenei was killed in strikes on Iran.