I think the age of criminal responsibility is too variable per individual child to pen down to a specific age.
10 year olds do not belong in jail, no matter what they have done.
If we simply lock ten year olds up, they are more than likely to come out and commit more crime.
Children who carry out serious offences need to understand the severity of their actions.
We run the risk of labelling children as criminals and building a cycle that children find it very difficult to break out of.
Children who commit crimes under the age of ten need mentoring, or placed in secure "family style" environments and have the opportunity to go out and receive the care they should have received in their own homes.
There should be attention on prevention and alternatives to custody.