The Police and DCP do not randomly turn up to schools and approach children in the playground. A report would have been made and they would have spoken to staff and been granted access to interview the child.
Staff will be aware who these 2 people were.
As far as I know children would not normally need to be remove from the school premises for interview.
I agree you need to step back and let things take their course. If you are being investigated and worried you could be charged, your interference could imply you are guilty.
A future question - What could happen if I am charged with—?