A two-year-old girl was seen lying in the road covered in blood on Tuesday after being hit by a moped as she crossed the street with her family.
The toddler was using Uxbridge Road in Acton, west London, with her mum and older brother when she was knocked down at around 6.30pm.
The girl remains in a critical condition in hospital.
The 19-year-old moped rider, who remained at the scene, was arrested on suspicion of dangerous driving and driving under the influence of drugs, and remains in custody.
Hanna Ayalew, 40, who lives next to where the accident took place, called 999 when she heard screaming and saw the girl bleeding on the road.
“I saw a pink toy scooter by the side of the road, but I don’t know if she was riding it when she was hit," she said.
“Luckily a doctor and a nurse has stopped to help the mother who was trying to hold the little girl."
She added: “I was in shock, I was crying because I’m a mother too and seeing that little girl lying there bleeding was heartbreaking.”
Wendy Corney, 56, who lives in front of the Vale junction where the accident occurred, also called the emergency services.
She said: “It was horrible really, I saw bags of shopping on the floor and the little girl was lying in the road.
“The guy who hit her was in shock and had taken off his jacket which he was trying to put around her head because she was bleeding.
“Her brother was there holding her hand and the mum was crouched over her.”
She said the girl’s father arrived later on a motorbike.
Another resident added: “My girlfriend heard a big commotion outside.
“There were around five police cars and five ambulances there."
Detective Sergeant Nush Puvitharan has appealed for anyone who witnessed or captured the crash on their dash-cam to contact police.
He said: "The incident happened as the girl and her family were crossing the street at traffic lights while other vehicles waited.
“Some of those road users would have seen the incident or may have recorded the events on dash-cam footage and, if so, I would urge them to come forward and speak to police.
“This information could prove vital in ensuring we can piece together exactly what happened in this incident.”
Watch the latest videos from Yahoo News UK