The Brazilian Air Force announced today that it has sent three investigators to Kazakhstan to participate in an investigation into the causes of the crash of the Azerbaijan Airlines plane.

The Brazilian-made Embraer passenger plane crashed yesterday near the city of Achtau, killing 38 people.

Brazilian investigators will “provide technical support” to the investigation being conducted by Kazakh authorities under the international rules known throughout the industry by their legal name as “Annex 13,” the Air Force said.

The plane was operating flight J2-8243 from Baku, Azerbaijan to Grozny, Chechnya. It crashed on the opposite shore of the Caspian Sea after experiencing an “emergency”.

The cause of the crash is not yet clear, but statements by unnamed officials have raised suspicions that Russian air defenses were involved in the crash.

Four Azeri sources with knowledge of the investigations told Reuters today that the plane was shot down by a Russian air defense system.

The investigation into the cause of the crash is ongoing and it is wrong to speculate before it reaches its conclusion, Kremlin spokesman Dmitry Peskov said today. According to Russia’s Civil Aviation Service, the aircraft may have been hit by a flock of birds.

The Kazakh authorities, for their part, said that they are neither able to confirm nor deny that the Azerbaijan Airlines plane was shot down by Russian air defenses.

An unnamed US official said today that there are early indications that a Russian air defense system may have hit the aircraft on Flight J2-8243.