A newborn baby is being cared for in hospital after she was found in a shopping bag by a dog walker in east London, the Metropolitan Police have said.
Officers are trying to trace the girl's mother, who they say will be in need of immediate medical attention.
The force were called to the junction of Greenway and High Street South in Newham by a member of the public who was walking their dog at around 9:13pm on Thursday night.
The baby was found wrapped in a towel inside the bag and is well and not injured, police said.
The Met Office has said the temperature was as low as -3C in London at the time the baby was found.
Chief Superintendent Simon Crick, who leads policing in Newham, said: "Thinking fast, that person kept the baby girl warm until London Ambulance Service paramedics arrived and checked her over before taking her to hospital.
"I am delighted to report that she wasn't injured in any way and is safe and well in the care of hospital staff."
Chief Superintendent Crick also said he was grateful to members of the public who stayed at the scene to speak with officers and medics, adding that their actions helped save the baby's life.
He added that the force is now "extremely concerned" for the welfare of the baby's mother who will have "been through a traumatic ordeal" and be in need of medical attention following the birth.
Chief Superintendent Crick said trained medics and specialist officers are ready to support the woman.
He urged her to walk into the nearest hospital or police station or phone 999.