A two-year-old boy and his 10-year-old sister were critically injured in a hit and run as they walked home after buying onions for the family's Eid celebrations, police have said.
Raham Saleem and his sister Sabam were knocked down by a silver Vauxhall Astra in Brudenell Road, Hyde Park, Leeds, at around 5.20pm on Saturday.
West Yorkshire Police said the driver slowed down to see what had happened, then sped away from the scene.
The children underwent surgery at Leeds General Infirmary, where they are in a critical condition.
Detective Superintendent Paul Taylor of the homicide and major inquiry team who is leading the investigation, said: "They went to the shop to buy some onions for their mam, preparing for the Eid celebrations today.
"They were crossing the road and they were struck by a vehicle, both were injured and underwent operations overnight. We are very concerned about their condition."
Having walked only a couple of hundred yards from the shop, they crossed near the Makkah Masjid Mosque. The road is used as a cut through locally, but has speed bumps, Mr Taylor said.
Detectives know the car is a mark four model, meaning it was made between 1998 and 2005. CCTV has already been examined and experts will study more footage in a bid to identify the car's registration number.
"We know the vehicle slowed down and we know they have then sped off," he said. "I would appeal to that driver to come forward so he or she can tell us what happened."
The Eid celebrations mark the end of Ramadan, the holy month of fasting observed by Muslims.