The President of the Russian republic of Tatarstan declared a day of mourning Monday after a Boeing 737 passenger plane crashed in the capital, Kazan, over the weekend, killing all 50 people onboard.
Those killed included Tatarstan President Rustam Minnikhanov’s son, Irek, and republican Federal Security Service department chief Lt. Gen. Alexander Antonov.
The jet, a Tatarstan Airlines Boeing 737 , bound from Moscow to Kazan with 44 passengers and six crew on board, crashed at about 7:30 p.m. local time (1530 GMT).
Crash investigators said the possible causes of the accident were a technical malfunction or pilot error. Flight recorders had not been located as of mid-morning Monday, RIA Novosti reports.