A Russian military transport plane was shot down near Belgorod, killing all 74 people on board, according to Russian military leaders, AP reported.

The Russian defense ministry claimed the aircraft was transporting 65 Ukrainian prisoners of war who were to be exchanged for Russian POWs and said the missiles that destroyed the aircraft were fired by Ukraine.

Verified video of the crash by a Belgorod resident shows an aircraft crashing near a residential neighborhood and exploding in a massive fireball. Ukrainian sources have neither confirmed nor denied their role in the crash. Russia has not produced any evidence to show that the aircraft was carrying POWs.

“We’ve seen the reports, but we’re not in any position to confirm them,” U.S. National Security Council spokesman John Kirby said.

Ukrainian officials confirmed that a prisoner swap was scheduled to take place. Previous prisoner swaps have involved Russian and Ukrainian forces agreeing to safe airspace to prevent tragedies. According to Ukraine, there was no agreement in place to protect the airspace in the region where the plane was shot down.

The most recent prisoner swap was brokered by the United Arab Emirates and was the largest swap to have taken place in the 700-day-old war. That deal saw 230 Ukrainians exchanged for 248 Russians. In all, Russia and Ukraine have swapped prisoners 49 times since the war began.

Ukraine regularly targets Russian military aircraft operating near the border. On January 15, Ukraine claimed to have destroyed a Russian spy plane equipped with radar and another aircraft used for command missions. Both aircraft are rare and expensive, making them high-value targets. In all, Ukraine claims to have destroyed more than 100 planes and 130 helicopters since the start of the war.

However, some experts believe that the two aircraft shot down last week may have been destroyed through accidental friendly fire, as Ukraine would have needed to position the anti-aircraft missiles close to the front lines for the western-supplied Patriot missiles to have been effective, Le Monde reported.

Ukraine has few available Patriot missiles and launch systems. Additional U.S. aid to Ukraine is currently on hold as legislators attempt to make a deal on border security.

It is difficult for observers to get reliable information about shootdowns from either Russia or Ukraine. Both military agencies regularly refuse to release details, and both sides have been accused of exaggerating claims.