The children have not been missing before and although they have packed clothes and taken money we are very concerned about them, particularly in this cold weather. It is believed they have left on their own accord.
We are continuing to carry out a number of enquiries to try and locate Sophie and Jack and are being supported by a significant number of force resources.
We are now appealing to the public to help us with this search - if you have seen either of the children today or have any information about where they may be, please contact us immediately.
More top news
Tonight: a transgender 8-year-old, how a horse is helping a boy with Asperger's and a nurse who would prefer not to be noticed.
As we go into the Bank Holiday weekend, the changeable weather pattern looks set to continue.
Labour leadership contender Andy Burnham has called for the House of Lords to be scrapped, saying it's "a national embarrassment".