International humanitarian law question

Here's a picture that an AFP photographer took yesterday:

A Palestinian youth throws a petrol bomb towards Israeli military armoured vehicles in the West Bank town of Bethlehem, January 28.

Are Israeli soldiers justified in shooting a youth like this who is throwing a bomb towards them? Or is there some special dispensation for 17 year olds to do whatever they feel like because the magic age of 18 makes them somehow more responsible?

This is not a theoretical question: at the same time this photo was taken the IDF appears to have shot and killed a 17-year old. Perhaps it was this very same person, although PalArab sources say that he was "only "throwing rocks.

UPDATE: Indeed, the "youth" was throwing a Molotov cocktail, not rocks.