A bird strike and even misfiring of an anti-aircraft missile are reported to be the possible cause of Wednesday's crash of an Azerbaijan Airlines passenger jet in Kazakhstan. Kazakh authorities are investigating.

The airliner, with 62 passengers and 5 crew members onboard, went down near an airport in Aktau in western Kazakhstan. Kazakh authorities say that 38 people were killed in the crash and 29 are being treated in hospital.

The plane had left Azerbaijan's capital, Baku, for Grozny in the southern Russian republic of Chechen.

Russia's aviation authorities said on Wednesday that as preliminary information, the plane hit a flock of birds, and as a result of the emergency situation, the captain of the plane decided to reroute to Aktau.

A video footage purportedly taken inside the aircraft shows oxygen masks coming down from the ceiling. A part of the plane's left wing was seen damaged through the window view.

Other footage shows the crashed plane on the ground with its underside facing upward, and its tail section with many holes.

These video clips were posted online.

A Russian independent news outlet says the holes on the fuselage may indicate that the plane could have been hit by an air defense missile, such as Russia's Pantsir-S1 system, rather than colliding with birds as Russian authorities indicated.

Azerbaijani President Ilham Aliyev has said he does not know the cause, and there are different explanations.

He said it is too early to comment on it, adding that the issue must be fully investigated.

The plane's flight recorder has already been recovered, and the governments of Kazakhstan and Azerbaijan are analyzing it to determine the cause of the crash.