A child was killed and another was injured after a BMW crash on a sports pitch in Kendal, Cumbria.
The driver, a man in his 40s, has been arrested on suspicion of causing death by dangerous driving.
Specialist police investigators cordoned off the area to begin their enquiries, police say.
The immediate family members of both children have been informed, according to officers.
Emergency services rushed to Kendal Rugby Union Football Club on Shap Road at 4.58pm following a report of a collision involving a car and two children on a pitch.
The second child was being treated by paramedics on Wednesday evening.
The car involved was a black BMW i40.
The chairman of Kendal Rugby Club Stephen Green posted on Facebook that the club was deeply saddened, saying: “Our thoughts are with their family and friends and we kindly ask for privacy for all involved at this difficult time.
“We are cooperating fully with the authorities as they conduct their investigation – the club and all facilities are temporarily closed while this is carried out.”
Cumbria Police say they are treating the collision as an isolated incident and there is no suggestion that it was terror-related. Anyone who saw the crash is asked to contact them.