Together with a fourth boy, they are also thought to have molested a 15-year-old girl.
The two girls, who are friends, called the police immediately after the attacks, which took place outdoors.
The boys deny the charges but admit that they were in Gamlestan at the time.
Prosecutor Håkan Johansson however has little doubt as to their involvement.
“It’s more or less solved,” he told newspaper Göteborgs Tidningen.