1 stick of dynamite releases ~2 MJ.
A typical hand grenade (like an M67) releases ~200-400 kJ.
If the girl reached 11-20 m, the explosion had at least 100 kJ - 1.2 MJ of energy. This is in the range of a military grenade or a large explosive firework, NOT a small firecracker.
不過佢個range 計得好闊