Concerns are growing for a 14-year-old girl who has been missing from her west London home for more than 48 hours.
Alice Gross, who has health concerns, was last seen at about 13:00 BST on Thursday when she left home in Hanwell.
Officers said they were "growing increasingly concerned" as to the whereabouts of the Brentside High School student.
Alice is described as being 5ft 2in tall, slim, with shoulder length light brown hair.
When she was last seen, she was wearing dark blue jeans, a dark green lacy cardigan and denim blue Van's shoes. She may also be wearing tartan-framed spectacles.
Her family have put out appeals on Facebook and Twitter.
In one Facebook message, the teenager's sister Nina Gross wrote: "The police have requested to hold off any non-police searches, as they are actively searching certain areas this morning, until further notice.
"But please continue to raise awareness with posts and posters."
Officers are conducting searches and house-to-house inquiries in the Hanwell area.