The 44-year-old is said to have been thrown in front of her lad’s pick-up.
It happened in Charlton, South East London, on Tuesday night.
The victim was named locally as Bella.
It is alleged the victim’s son got behind the wheel of a pick-up truck.
One source said: “She was hit by the van driven by her own son and killed.”
Her son was one of five men who were arrested yesterday on suspicion of causing death by dangerous driving.
He is said to have surrendered himself at a South London police station for questioning.
The driver is said to be “distraught” and the source added: “This has led to bad blood.’’
Shocked neighbours said they heard a “big bang” at the time.
Friends and family left flowers and a beer bottle at the cordoned off scene.
One tribute read: “We can’t believe it’s real. You will be missed so much.”
A Met Police spokesperson said officers and an ambulance attended after being called just after 10.30pm to reports the woman had been hit by a van in Atlas Gardens, Charlton.
The spokesperson added: “Despite their efforts, the woman died at the scene a short time later.
“The woman’s next of kin has been informed and specially trained family liaison officers will provide them and their family with support.”
Detectives from the Met’s Specialist Crime Command are leading the investigation and appealed for witnesses to come forward.
Detective Chief Superintendent Trevor Lawry, local policing commander, said: “This is a tragic incident and my thoughts are with the woman’s family and friends at this incredibly difficult time.
“A dedicated team of detectives are continuing to piece together what happened and they will remain at the scene throughout the day whilst they carry out these enquiries.
“Local neighbourhood officers will also be in the area to respond to any concerns you may have.”
A post-mortem examination is due to take place to establish the victim’s cause of death.
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