A military transport plane that Russia said was carrying 74 people, including 65 Ukrainian prisoners of war to be swapped, crashed Wednesday near Ukraine. All aboard were killed.

Russia said the crash occurred in a border region near Ukraine on Wednesday.

According to the Associated Press (AP), it wasn’t immediately clear what caused the crash in the Belgorod region. Governor Vyacheslav Gladkov didn’t specify who was on the plane.

The AP also said it could not confirm who was on board, and Ukrainian officials cautioned against sharing unverified information.

Nevertheless, citing the ministry, Russian state news agency RIA Novosti, reported that the prisoners of war were being transported to the border region for a prisoner exchange.

“Footage of the crash posted on social media showed a plane falling from the sky in a snowy, rural area, and a massive ball of fire erupting where it apparently hit the ground. Firefighters, ambulances and police rushed to the site of the crash in the Korochansky district of Belgorod, state news agency Tass said, citing a local emergency services official,” the report from AP said, adding that two senior Russian lawmakers alleged, without providing evidence, that the plane was brought down by missiles launched by Ukrainian forces.

Shortly before the crash, Gladkov said on his Telegram channel that a “missile alert” had been triggered in the region and warned residents to take shelter.

Meanwhile, Ukraine’s Coordination Headquarters for the Treatment of Prisoners of War said it was looking into the crash but did not immediately provide any information. Instead, it cautioned against sharing “unverified information.”

The plane is designed to airlift troops, cargo, military equipment and weapons. It can carry up to 225 troops, according to Russia’s military export agency.