Moscow appears to have lost four military aircraft in downings on Saturday in the Bryansk region of Russia, some 50 kilometers northeast of the border with Ukraine.

Two Mi-8 military helicopters and two fighter jets — an Su-34 and an Su-35 — suffered crashes on Saturday, according to reports by Russian state media and pro-Kremlin bloggers. All crew members of the aircraft died, according to the reports.

“Two Mi-8s, one Su-34, and one Su-25 were lost. Tragedy,” Russian propagandist Andrei Rudenko reported. “They were hit near the border of the Russian Federation and most likely with air-to-air missiles,” he said. The cause of the downings could not be confirmed.

Russian authorities confirmed only one aircraft downing, of an Mi-8 helicopter near the village of Klintsy in the Bryansk region, and did not give a cause for the crash. Russian media outlet Readovka reported that the aircraft were shot down from the Chernihiv region in northern Ukraine.

Numerous videos posted to social media appear to show the burning remains of an Su jet and an Mi helicopter. POLITICO could not independently verify the videos.

Kyiv has not claimed responsibility for downing any of the helicopters or jets.

Russian media outlet Mash reported that Moscow has launched a hunt for “saboteurs” in connection with the aircraft downings. “According to our information, authorities are looking for saboteurs who may be involved in the attack on the Mi-8 and Su-34,” Mash said.

One civilian was reported wounded and five residential buildings were damaged as a result of one of the helicopter crashes.

Ukrainian Air Defense Forces spokesman Yuriy Ignat refused to confirm or deny information regarding the aircraft downings. “Of course, I won’t tell you anything,” Ignat told POLITICO.

Russian media website Kommerstant reported that all four aircraft that crashed on Saturday were part of a group heading to bomb the Chernihiv region in northern Ukraine.