The parents of an 11-year-old boy killed in a hit and run collision have appealed to the suspected driver to come forward. Sam Riddall died after a car mounted the pavement and ran into him as he walked home from a church youth service in Westbury-on-Trym, Bristol, last Friday evening. Sam's parents, Martin and Rachel Riddall, have asked 27-year-old Hannah Saaf - whose name was released by police earlier this week - to make contact with detectives. Mrs Riddall, 39, who works for Christian organisation Agape, told a press conference in Bristol: "I am here to appeal to Hannah as a mum, who has lost a precious son. "Please come forward, Hannah, and talk to the police so we can begin to put our lives back together." Ms Saaf, a mother of twins from Kingswood, Bristol, is the registered owner of the white Ford Focus estate car which careered off Eastfield Road at around 9.15pm last Friday. The vehicle hit Sam, who was walking along with three other children and Dr Peter Harbord, the father of one of his friends, after leaving a youth club service at the Henleaze and Westbury Community Church. Witnesses then saw the female driver run from the car towards Cote Lea Park. She was described as white, with long blonde hair and in her mid-30s. Mr Riddall, 45, a former RAF mechanic who works for Campus Crusade for Christ International, said: "This is an impossible time for us. We have three other children and they are full of questions that we can't even begin to answer." He added: "Sam loved Jesus and it's comforting for us to know he's with him now. But we miss him very much indeed. And we wish he was here with us every second of the day." Police earlier said there had been "a confirmed sighting" of Ms Saaf in the centre of Bristol on Saturday afternoon, and reported sightings in Wiltshire, Brighton and Bath. The three other children involved in the incident, all thought to be aged 11, were uninjured, while Dr Harbord received minor injuries and was released from hospital later that evening.