Two of the attacks happened on Sept. 21, and the third attack happened on Oct. 5, the BBC reported.
Authorities said they are worried the attacks could escalate.
"It is obviously very unusual and very worrying, that someone so young is committing such appalling attacks on women," said head detective Colin Larkin. "Whatever the young boy's motivation, this is not a practical joke or a prank. His actions are disturbing."
Police said they believe the boy has been caught by surveillance camera.
"Given his young age, I would appeal to anyone who may know him -- schoolteachers, community leaders or possibly even family members -- to either alert the police or bring this young man to a police station as soon as possible," Larkin said. "We cannot allow these sexual assaults to escalate and we need to find him."
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