A 36-year-old man has been arrested in connection with a hit-and-run incident which left a two-year-old boy and his 10-year-old sister fighting for their lives.
The man is being questioned by police after Raham Saleem and his sister Sabam were knocked down by a Vauxhall Astra in Brudenell Road, Hyde Park, Leeds, on Saturday.
He has been arrested on suspicion of dangerous driving, failing to stop at the scene of an accident and failing to report an accident, said West Yorkshire Police.
A force spokesman said: "At around 9.30pm this evening police arrested a 36-year-old Leeds man in connection with the incident. He was arrested on suspicion of dangerous driving, failing to stop at the scene of an accident and failing to report an accident.
"Police have also recovered a vehicle in connection with the investigation. The 36-year-old remains in custody tonight for questioning by officers."
Police said Raham and Sabam were hit at around 5.20pm on Saturday after buying onions for the family's Eid celebrations. A cousin, who was with the children, escaped injury. Officers 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 Sabam remains in a critical condition. West Yorkshire Police said her brother was now improving and has been moved out of the intensive care unit.
Police earlier released an image of the silver or grey Vauxhall Astra mark 4 believed to have been involved in the collision. Detectives also said they believed a woman seen on the street at the time may have witnessed what happened and urged her to contact them.
On Sunday Detective Superintendent Paul Taylor, who is leading the inquiry, said Sabam's father thinks she is "the apple of his eye", while her brother was due to start nursery in October.
On Monday, 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."