MOSCOW: Russian mercenary chief Yevgeny Prigozhin and some of his top lieutenants were presumed dead in a plane crash that was widely seen Thursday as an assassination to avenge a mutiny that challenged President Vladimir Putin.

Meanwhile, Putin broke his silence on the crash, expressing condolences to the families of those who were reported to be aboard the jet and referring to “serious mistakes” made by Prigozhin.

The founder of the Wagner military company and six other passengers were on a private jet that crashed Wednesday soon after taking off from Moscow with a crew of three, according to Russia’s civil aviation authority. Rescuers found 10 bodies, and Russian media cited anonymous sources in Wagner who said Prigozhin was dead. But there has been no official confirmation.

If the deaths are confirmed, the crash would be the most serious blow the group has ever suffered to its leadership. The passenger manifest included Prigozhin and his second-in-command who baptized the group with his nom de guerre, as well as Wagner’s logistics chief, a fighter wounded by U.S. airstrikes in Syria and at least one possible bodyguard.