The leader of the Wagner group died in a plane crash.

A flight from Moscow to St. Petersburg collapsed on Wednesday, killing all 10 people on board, the Associated Press reported, citing Russian emergency officials.

The leader of the Wagner mercenary group, Yevgeny Prigozhin, is said to have been on the plane’s passenger list, but it is unclear whether he was on the plane.

Unconfirmed reports say that the plane was owned by Prigozhin, who founded the private security company Wagner.

The Russian news agency Tass, citing emergency officials, said the plane was carrying three pilots and seven passengers. Authorities said they were investigating the crash in the Tver region, about 100km north of Moscow.

Prigozhin, whose army fought alongside the Russians in Ukraine, staged a short-lived uprising in June against the country’s military leadership. The Kremlin says he will be in exile in Belarus, after which his army will be deployed, or they will go to that country or join the Russian military.