ADEN (Reuters) - Southern separatists opened fire on a military academy graduation ceremony in Yemen’s port city of Aden on Saturday, killing a cadet and wounding at least two others, witnesses said.

The incident is the latest in a series of killings and bombings in the southern city, the temporary headquarters of the internationally recognized government of President Abd-Rabbu Mansour Hadi, who was expelled from the capital Sanaa in 2014 by the armed Houthi group.

One academy officer said southern separatist forces fighting alongside a Saudi-led coalition against the Houthis had opened fire from their mountain base across from the academy.

“When the graduation ceremony began they opened fire with machine guns because the academy had flown the unification flag of Yemen,” he told Reuters, speaking on condition of anonymity.

Another witness said two people had been injured and that the ceremony was moved inside, and cut short.

The rising tension between the southern separatists, who are allied with the United Arab Emirates, and Hadi’s government comes ahead of U.N.-sponsored consultations between the warring Yemeni parties next month in a bid to end the more than three-year-old conflict.

The UAE and Saudi Arabia are leading a Sunni Muslim Arab coalition that intervened in Yemen’s war in 2015 to unseat the Iranian-aligned Houthi movement and restore Hadi’s government.