Manchester Crown Court was told that the boy - who cannot be named for legal reasons - wore a balaclava mask and brandished a knife when he waylaid the two girls in the Waterworks Country Park at Oldham, Greater Manchester.
The boy had pleaded guilty to rape and indecent assault on 31 May this year. He admitted kidnapping both girls on the same date; kidnapping two other girls last March and indecently assaulting them; and indecently assaulting a girl, 11, the day before the rape.
The court heard how the two double attacks involved the boy wearing a balaclava and brandishing a knife. Both were shown in court.
Michael Shorrock QC, for the prosecution, told the court all the incidents took place in the same area. In the most serious, two 12-year-old girls were on their school holidays.
"They decided to go for a picnic. They set off shortly after midday on their bicycles," Mr Shorrock said. "When they finished their picnic, they played for a bit then started to make their way back pushing their bikes.
"As they approached the road, they were confronted by the defendant. They didn't know who he was. He was wearing a black balaclava pulled over his face. He produced a knife and threatened the girls. He made them go up a path to a secluded spot."
Mr Shorrock said the boy forced both girls to undress, made them lie on the ground and tied them by the wrists to a tree with their shoe laces. The girls later told police that they were blindfolded, gagged and hit.
"The girls managed to free themselves. They were seen, both naked and very distressed, by two passers-by," Mr Shorrock said. The attack on 19 March involved two girls, 12 and 11, who were playing in a disused quarry. They saw a boy coming towards them and ran towards a main road.
"Before they could get there the boy caught up with them. By this time he had a balaclava covering his face," Mr Shorrock said. He produced a knife and forced the girls to go with him to a secluded spot where he indecently assaulted them. When one girl started screaming the boy threatened her with his knife and said: "Do you want to die?"
The attack ended when a horse rider appeared.
The indecent assault on 30 May took place when the boy approached children playing in an air-raid shelter and indecently assaulted a girl, 11. Her mother contacted the police when she heard of the double attack the following day.Reuse content