The boys were aged 4 and 10. The driver of the car, believed to be the boy's mother, and another female passenger, remain in a stable condition in hospital.
The crash occurred on the northbound carriageway near junction 15 at around 11.25am this morning.
The motorway has now reopened.
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Windy throughout the weekend with gusts of 50mph especially around the coast. Saturday will be drier and brighter than Sunday
After saying she wanted "just a card" for her birthday Betty Musker is celebrating her 104th with over 6,000 cards from around the world.
Looking windy throughout Saturday and Sunday with gusts of 50mph at the coast and high tides. Brighter and drier on Saturday than Sunday