A Russian passenger jet caught on fire on Sunday, leaving at least 41 people dead. The plane was attempting an emergency landing, the airline has confirmed, when the fire started on the back of the aircraft.

“[The plane was] being forced to return to Sheremetyevo International Airport due to technical reasons,” Aeroflot explained. “The fire has been extinguished. Medical assistance is being provided to those injured in the incident. Passengers left the aircraft via the emergency exits. An investigation has been launched into the incident, and Aeroflot has activated its crisis response team.”

Why an emergency landing was attempted only half an hour after take off, or what caused the fire, is yet unclear. However, the local media is reporting that a lightning had hit the back of the plane, making significant damages to the plane’s communication system. The plane failed to land smoothly and broke its landing gear, the shards of which flew inside the engine and started the disastrous fire. Neither the airline or the Russian government.

“All instructions have been given to conduct the most thorough investigation [to carry out] the necessary orders to find out the cause of this accident,” Kremlin spokesperson Dmitry Peskov said. “The president extends his deep condolences to those who lost their near and dear in this incident.”