Five teenage girls who are said to have shown an interest in going to Syria have been barred by a High Court judge from travelling abroad.
The two 15-year-olds and three 16-year-olds were made wards of court by Mr Justice Hayden.
The judge's decision prevents them from leaving the jurisdiction of England and Wales.
He made the ruling at a hearing in London after Tower Hamlets local authority raised concerns.
The judge, who said the girls could not be identified, also made orders removing their passports and those of a number of adults involved in their care.
Mr Justice Hayden said he made the order involving the adults because of evidence that, in at least one other case, young girls had travelled on passports belonging to members of their family.
More importantly, there was evidence suggesting the family members in the case had not been full and frank with social services, and that the girls had been moving to a more radicalised position.
He said: "It seems to me that that must have been known to the parents and they deliberately did not share it with the authorities who were keen to protect these vulnerable young girls."
The judge, who made a similar order in relation to a 16-year-old boy earlier this week, admitted it was a "draconian" step, as was the removal of a passport.
He said: "But the risk contemplated here is as grave as it can be for it is common knowledge that so many have lost their lives in Syria and so many have gone knowing that would be likely."
The girls and adults concerned, who were not in court, can challenge the emergency ruling at a future date if they wish.
Three girls who attended Bethnal Green Academy in east London disappeared last month and are believed to have travelled to Syria to join Islamic State militants.
Shamima Begum, Amira Abase, both 15, and Kadiza Sultana, 16, took flights to Istanbul in February.
The schoolgirls are thought to be staying at a house in the IS stronghold of al Raqqa, Sky sources have said.
Their disappearance led to criticism from Turkey's deputy prime minister, who said officials had not been given enough warning about them going missing.
Three young British men suspected of planning to join IS militants in Syria were arrested in Turkey earlier this week.
CCTV video of the teenagers was taken at an airport in Istanbul just before they were stopped allegedly heading to the Syria border.
The trio, two aged 17 and one aged 19, were arrested and flown back to the UK but have since been released on bail.
Security services estimate 600 Britons have gone to Syria or Iraq to join militant groups, including Mohammed Emwazi, also known as "Jihadi John", who has appeared in several IS beheading videos.
