Pictures of Chinese Executions by Beheading we already have on Best Gore were taken in the early 1900s. Since then, Chinese executioners modernised their arsenal and come mid to late 20th century, they started executing people with a gunshot to the head. What these three teenage girl were accused of is uncertain, but they were executed despite their age. They were lined against the wall of dirt and took a rifle shot in the skull. They were either not as young as they seem from the photos, or they do also execute underage people in China.
Notice how there are soldiers who get to hold the condemned while they are being executed. They know brain matter is about to start flying uncontrollably so they bend out of their way to avoid it as much as they can.
The girls look very young – in their teens but guessing correct age of Chinese girls can be tricky. There was something like a cover story with these pictures which said that they were spies, a crime for which there is a capital punishment in China, no matter the age. If that story is real, then they sure train their spies young (not sure who would have trained them, some other country perhaps?). Someone however mentioned that they were executed on drug trafficking charges. Perhaps someone who speaks Chinese can translate the signs the executioners made them wear before the sentence was carried out.