Massive and explosive launch failure of a Proton-M heavy lift rocket with 3 GLONASS navigation satellites.
The Proton-M rocket began losing control mere seconds after liftoff, careening and spinning before arcing back down and breaking up to explode on the ground near the launch facility.
Proton rockets are fueled by dinitrogen tetroxide and unsymmetrical methylhydrazine, both highly reactive hypergolic propellants which are corrosive and poisonous. The debris cloud is highly toxic. Launch crew were safe in an underground bunker and are unhurt.