Russia’s civil aviation agency says an Azerbaijan Airlines plane which crashed in Kazakhstan on Wednesday had decided to reroute from its original destination due to dense fog and a local alert over Ukrainian drones.

The Embraer EMBR3.SA passenger jet was flying from the Azerbaijani capital of Baku to Grozny in Chechnya, Russia, when it crashed on Wednesday.

The plane crashed a few miles from an airport in the city of Aktau in western Kazakhstan. Of those aboard, 38 were killed and 29 survived the crash.

Dmitry Yadrov, head of Russia’s civil aviation agency, said his country would provide comprehensive support to Kazakh and Azerbaijani investigations looking into the crash.

He said, “Ukrainian military drones were carrying out terrorist attacks on civilian infrastructure … at the time.”

At the time there was also heavy fog over Grozny, he said. He described conditions as “very complicated,” adding, “The pilot was offered alternative airports. He took the decision to go to Aktau airport.”

Azerbaijan Airlines on Friday blamed the crash on unspecified “physical and technical interference”. It did not say where the interference came from or provide any further details.

A member of Azerbaijan’s parliament, Rasim Musabekov, told the Azerbaijani news agency Turan on Thursday that the plane was fired on while in the skies over Grozny and urged Russia to offer an official apology.

Yadrov did not comment on the statement by the Azerbaijani lawmaker, and said it is important to wait for an investigation to finish its work in order to understand what happened.

When asked about Musabekov’s statement, Kremlin spokesman Dmitry Peskov declined to comment, saying that it would be up to investigators to determine the cause of the crash.

“The air incident is being investigated, and we do not believe we have the right to make any assessments until the conclusions are made as a result of the investigation,” Peskov said in a conference call with reporters.

Following the crash on Wednesday, Azerbaijan Airlines suspended flights from Baku to Grozny and Makhachkala. It also announced on Friday that it would also halt service to eight more Russian cities.

The majority of Russian cities and towns have been repeatedly targeted by Ukrainian drone and missile strikes, making civil transportation over Russian airspace dangerous and difficult.