Colonel Alexei Sharov became the latest high-ranking Russian official to die in what has become the country’s biggest loss of military higher-ups since World War II. His death was announced by Ukrainian armed forces on social media Tuesday.

The commander of the 810th Guards Separate Order of Zhukov Brigade in the Russian Marines, Sharov was reportedly killed in Mariupol, a city in which over 100,000 people have been trapped amid a siege by the invading Russians…

Sharov’s death comes after the death of Colonel Nikolay Ovcharenko, Commander of the 45th Engineering Regiment.

Sharov is the fifth colonel to die and marks 15 of Russia’s military commanders to have died in the invasion, according to The Sun. Foreign Policy reported that Moscow has suffered its highest casualty rate among top brass since the WWII.