Explain what happened when Malala was shot in I Am Malala.

Malala explains what happened when she was shot in the prologue to the book.
Malala, other girls from her school, and three teachers were on the school bus. The bus was stopped "less than 200 metres" from an army checkpoint. A man "in light-coloured clothes" told the driver that he needed information about some of the girls on the bus. Meanwhile, a second man approached the back of the bus. At first, the girls thought that this second man might be a journalist come to speak to Malala about her campaign for girls' education.
This second man, wearing "a handkerchief over his nose and mouth," stepped up onto the tailgate of the bus, leaned into the van, and asked, "Who is Malala?" Several of the girls looked at Malala, who was the only girl whose face was not covered. At this point, the second man took out a pistol and fired three shots.
The first bullet entered Malala's left eye socket and emerged beneath her left shoulder, at which point she slumped forward, blood coming from her left ear. The other two bullets hit the girls who were sitting next to Malala.