Police who found three brothers who went missing four days ago said there may have been a plan to spirit them out of the country.
Remus, Janko and David Matloch, aged 15, 12 and 10, failed to return to their foster carers' home in Sunderland, after setting out on a tea-time bike ride to a local park.
Instead, they caught a Metro to Newcastle, then took a pre-booked taxi to London and spent two nights in the capital before heading for Birmingham.
All the time with adult assistance, the brothers were then taken to Oswaldtwistle in Lancashire, where they were found this afternoon, safe and well.
A total of seven people have been arrested and the boys will be taken back to the North East later to be reunited with their foster parents.
Their natural father, who is of Romany origin, was deported to Romania after serving an eight-year prison sentence in this country for people trafficking.
The boys' mother was investigated for criminal matters and left the country earlier this year.
Northumbria Police said the brothers had been living happily with their foster parents for 18 months.
Superintendent Alan Veitch, who led the major investigation to find them, said it was "entirely possible" that the plan was to get the boys out of the country.
He said: "I think it has been quite organised and orchestrated.
"This was all planned and arranged in advance. By who, I don't know.
"This is what we need to get to the bottom of."
Two men, aged 47 and 22, and a 23-year-old woman were arrested in Lancashire. A 37-year-old was arrested in London yesterday and a 41-year-old Newcastle man was also helping police with inquiries.
A man aged 34 and a woman of 39, who were arrested at an address in Birmingham on Wednesday evening, remain in custody in the West Midlands.
Mr Veitch said: "We are delighted that the three boys have been found safe and well. We are planning to reunite them with their foster parents as soon as we can.
"We will need to speak to the boys over the next few days to piece together the full circumstances of what has happened, but of course we are just so pleased for them and their foster parents that this has been brought to a safe conclusion and that we have got the boys back."