Thames Valley Police is appealing for witnesses following a fatal road traffic collision on the M1 northbound between junctions 14 and 15 near Milton Keynes.
It happened at around 11.10pm Monday (9/8) and involved a white Vauxhall Astra and a Scania HGV.
Two children, aged 4 and 10, who were passengers in the Astra tragically died.
Their next of kin have been informed and are being supported by specially trained officers.
Another child passenger in the Astra and the driver were taken to hospital with injuries but have since been discharged.
The driver of the HGV was uninjured.
A 35-year-old woman from Derby, has been arrested on suspicion of causing death by dangerous driving and driving a motor vehicle when above the prescribed limit of alcohol. She remains in custody.
Investigating officer, Sergeant Dominic Mahon, of the Serious Collision Investigation Unit at Bicester, said: “My thoughts remain with the family of the two children who sadly died at this extremely difficult time.
“We are appealing for anyone who may have witnessed this collision or anyone who may have dash-cam footage that may have captured what happened or either of the vehicles prior to the collision to please get in touch.
“You can make a report by calling 101 or online, quoting reference 43210356500.”