Police are urgently looking for a three-year-old girl who called the ambulance service to say her mother had fallen and was not moving.
West Yorkshire Police said the youngster made the lengthy 999 call at 10.53am on Monday but, despite extensive inquiries since then, officers have been unable to identify where it came from.
A spokesman said she gave her name as Ellie and told operators her mother was called Stacey Hall.
She said her house number was 23 and had "Court" in the street name. She said her grandparents lived in Bridlington, East Yorkshire.
Detective Chief Inspector Lisa Griffin said: "We urgently need the public's help to identify exactly where Ellie and her mum are.
"We are hoping that someone out there who knows the family will recognise the pieces of information that the ambulance call-taker managed to get from her and will get in touch.
"We are treating this situation extremely seriously as it appears we have a woman in need of urgent medical attention and a vulnerable little girl who will also need our help.
"I want people to listen very carefully to Ellie's voice and to think about the pieces of information that we have and let us know immediately if they recognise who Ellie and her mum are and, most importantly, where they live so we can get help to them."
During the call, which lasted 33 minutes, Ellie told the call-handler that she was nearly four years old and that her mother had fallen over and would not get up.
She said she had shouted at her mother and wiggled her but she remained on the kitchen floor with a piece of toast in her hand, not moving. The spokesman said she said the front and back door were locked and she could not get out of the house.