The White House on Friday said initial signs pointed to Russian air defenses downing a passenger plane that crashed over Kazakhstan and killed 38 people. White House national security spokesperson John Kirby told reporters that the U.S. has "early indications" Russia was responsible but declined to say much more, citing an ongoing investigation. "We have offered our assistance to that investigation, should they need it," Kirby added. The Azerbaijan Airlines flight, an Embraer 190 aircraft model, was carrying 67 passengers when it crashed on Wednesday near the southwestern Kazakhstan city of Aktau on the Caspian Sea. The plane was headed from Baku to the city of Grozny in Russia's Chechnya republic, a region that has frequently activated air defenses to take out Ukrainian drones amid the war against Kyiv. Kazakhstan is leading an ongoing investigation, but a preliminary report seen by Azerbaijan news site Caliber indicated that a Russian Pantsir-S air defense system knocked the plane down. Azerbaijan Airlines said in a Friday post on the social platform X that the airplane was downed by "physical and technical external interference." The airline has suspended several flights to certain areas of Russia, including Grozny. The Kremlin on Thursday cautioned against speculation and said the investigation was ongoing. Investigators have said an oxygen cylinder blew up on the aircraft in the passenger cabin, though it's unclear how that happened. Russian aviation officials have claimed a bird strike was responsible for the explosion.