Police have released an image of a car they believe was involved in a hit and run incident which has left a two-year-old boy and his 10-year-old sister fighting for their lives.
Raham Saleem and his sister Sabam were knocked down by the car on their way to buy onions for the family's Eid celebrations.
Officers said the driver slowed down to see what had happened, then sped away from the scene.
They were hit by a Vauxhall Astra in Brudenell Road, Hyde Park, Leeds, at around 5.20pm on Saturday.
The children underwent surgery at Leeds General Infirmary where Sabam remains in a critical condition.
But West Yorkshire Police said her brother was now improving and has been moved out of the intensive care unit.
Now the investigation team has released a picture of a silver or grey Vauxhall Astra mark 4 (1998-2005) they urgently want to trace.
Two-year-old Raham, who was struck by the car along with his sister, is said to be improving
Detectives said they are continuing to trawl through CCTV.
They believe a woman seen on the street at the time may well have witnessed what happened.
Detective Superintendent Paul Taylor who is leading the inquiry, said: "A major investigation remains ongoing into what has been a catastrophic incident for Sabam and Raham's family on what should have been one of the happiest weekends of their year.
"Specialist officers are working to support the family who are clearly extremely distressed, and for their sake we ask anyone who can help us more quickly find the driver responsible for this collision to come forwards now."
"We can now release a CCTV image of the car which we believe was responsible and ask that anyone who recognises this vehicle should contact us as a matter or urgency.
"We also know there was a woman who was on the street at the time who we have not spoken to yet and would ask her to make contact with us as soon as possible."
10-year-old Sabam
Mr Taylor said: "We are making progress with this investigation which is drawing on specialist resources from across the force, including homicide officers and our specialist Major Collision Enquiry Team.
"We have received a lot of support from residents who are helping us investigate a truly shocking incident in a very close knit community and are determined to leave no stone unturned to locate this driver.
"Clearly it remains the case that it would be better for this individual to contact us before we come to see them."
Yesterday, Mr Taylor said Sabam's father thinks she is "the apple of his eye", while her brother was due to start nursery in October.
Officers have said the children had walked a couple of hundred yards from the shop when they crossed near the Makkah Masjid Mosque.
The two children went on the errand with a cousin, who escaped injury.
The road is used as a short-cut locally, but has speed bumps.
The children's aunt, Saima Rafique, told BBC Look North her niece's condition was very serious.
"We want her home," she said. "I really want my princess home."