Whatever bag/rope he threw did it hit the electric wire and the electricity travel from the stuff inside hitting him?
Looks like whatever they threw up there was probably conductive, shorted out across the power lines and instantly vaporized just like a fuse would. The resulting explosion blew the other two guys off the ladder and their feet. Lucky Darwin wannabes....
The guy on the ladder was probably fixing the electric wires, the guy on the curb threw him a coil of spare electric wires which was such a bad aim that it hit the existing wires instead of landing on the hands of ladder guy
