The launch of the Proton-M launch vehicle with a DM-03 accelerating unit and three Glonass-M navigation satellite vehicles was broadcast live on Russia 24 channel and on the Roskosmos website. At about the tenth second of the flight, the rocket suddenly changed its trajectory, caught fire, fell into the territory of the Baikonur cosmodrome and exploded.
One of the probable reasons is the loss of stability: the rocket bent down first to one, then to the other side. This could happen either due to a failure of the control system, or due to a problem with the combustion chambers in the engine.
It is worth recalling that in 2010 a similar incident occurred. However, the cause of the fall of the launch vehicle was different: then 03 was accidentally filled with tons of excess oxidizer in the DM-1,5 upper stage.
Currently, 23 active satellites are used for navigation, 4 is still in reserve, and 1 is in maintenance. On the eve it became known that one of the active devices, for some unknown reason, stopped transmitting a signal to Earth.