A missing mother and her four children are feared to be travelling to war-torn Syria, Scotland Yard believes.
Police are trying to trace Zahera Tariq, 33, her sons Muhammad, 12, Amaar, 11, Aadid, four and daughter Safiyyah, nine, who were last seen at her home address in Walthamstow, east London, on Tuesday.
They are believed to have flown from London City Airport to Amsterdam later the same day and may now be on their way to Syria, police said.
Commander Richard Walton, from the Metropolitan Police's Counter Terrorism Command, said relatives of the mother are "extremely worried".
He said: "We're concerned about Zahera and her four children and we're doing all we can to work with our partners and colleagues both here and abroad to try and locate them and make sure they are all safe and well.
"Whilst we do have some concerns that Zahera may be thinking of travelling to Syria, there is no current information to suggest that she's already travelled there.
"Her family are extremely worried about her and her three sons and daughter and we would urge anybody with information to contact us as soon as possible."
A family member contacted police on Wednesday to report the family of five missing, and raised concerns they could be on their way to the conflict zone.
Detectives later found the family had been captured on CCTV at London City Airport prior to their flight to the Netherlands.
The children are pictured wearing rucksacks while their mother pushes a trolley loaded with four suitcases.
Several cases have emerged in which women and children from the UK are feared to have gone to parts of Syria controlled by the so-called Islamic State.
In July it was reported that several members of the same family from Luton, including three children, were feared to have travelled to Syria after a holiday in Bangladesh.
Scotland Yard recently confirmed that it believed more than 40 women and girls had travelled to Syria from Britain in the last year.