An Azerbaijan Airlines plane that crashed on Christmas Day was “likely shot down by a Russian military air defence system,” a UK-based aviation security firm has said. The community is coming together to remember a man killed in a Waukesha County crash that happened on Tuesday, Dec. 24.

The flight was en route from the Azerbaijani capital of Baku to Grozny, in Russia’s south, when it diverted and attempted an emergency landing in Kazakhstan.

T hursday is an official day of mourning in Azerbaijan as an investigation is underway to determine what caused an airplane carrying 67 passengers to crash on Christmas Day in Kazakhstan, killing 38 and leaving at least 29 survivors. Video posted by CNN shows the plane crash-landing, exploding into a fireball and plumes of black smoke.