An urgent manhunt is under way after a father abducted three boys from their foster home in south London, the Met Police said.
Detectives are looking for Imran Safi, 26, who is said to have threatened the foster carer with a knife in Coulsdon last Thursday.
He is accused of taking Bilal, Mohammed Ebrar and Mohammed Yaseen – aged six, five and three.
Eight people have been arrested in connection with the abduction.
All eight people, aged between 17 and 37, were arrested in Croydon and have been bailed to a later date, the Met Police said.
More than 100 officers are currently working to locate the three brothers and an image of Mr Safi has been distributed to all UK ports.
Met Police Commander Jon Savell said it was “an absolute priority” to find the three children.
“They have been taken from a place of safety and we are growing increasingly concerned about their wellbeing, particularly as we remain in the midst of a global health crisis.
“While we do not believe at this time there is any immediate risk to their physical safety, their location, access to accommodation, healthcare, and other provisions is entirely unknown. We are concerned about the longer-term impact of this on all three children.
“An intense investigation into how this abduction was planned and carried out is being led by detectives in south London, alongside a manhunt being led by specialist detectives within the Met.”
The three children were playing in the garden while their foster carer was inside the house on Coulsdon Road when they were taken, detectives said.
The foster carer, who told officers that Safi threatened her with a knife, did not suffer any serious physical injuries in the incident but is “understandably distressed”.
A red Nissan Qashqai, with the registration PK13 WFO, is thought to be involved in the abduction.
Shortly after the children were taken an all ports alert was issued, meaning Mr Safi’s image and details were circulated to all ports and borders.
Mr Safi is an Afghan national and has links to Pakistan but police do not yet know if he has travelled overseas.
Detectives are working closely with national and international agencies to ensure any movement into foreign countries is identified.
Ch Supt Dave Stringer said that the incident would “understandably send a shock” to the local Croydon community.
“We know there are people with detailed knowledge of the whereabouts of these children, and we fully appreciate there may be very good reasons for those individuals not wanting to come forward,” he said.
“But right now I would strongly urge them to do the right thing and assist us in locating them.”