The crash happened when a minibus overturned as it travelled south at the Haggs junction on the M80 near Cumbernauld, central Scotland at 2.30am(BST) on Monday.
Police said both the dead and eight of the injured were members of the same family. The other passenger was a family friend.
The two adults and nine children, aged between four and 15, came from the Aberdeen area but police have not yet released details of their identities.
The 38-year-old man who was driving the vehicle and his son died at the scene.
Another passenger, a 13-year-old boy, suffered serious internal injuries in Falkirk Royal Infirmary, the hospital where all the injured were taken for treatment.
No other vehicle was involved in the accident. The M80 was completely closed for nearly six hours and the Haggs slip road will remain closed until further notice, police said.
Officers have appealed for witnesses and said a report will be submitted to the procurator fiscal.
Northern Ireland
Scotland
Wales
England
Next steps for peace
Blairs' surprise over baby
Bowled over by Lord's
Beef row 'compromise' under fire
Hamilton 'would sell mother'
Industry misses new trains target
Quins fightback shocks Cardiff
(From Sport)
Vodafone takeover battle heats up
(From Business)
IRA ceasefire challenge rejected
Thousands celebrate Asian culture
Christie could get two-year ban
(From Sport)
Colleagues remember Compo
(From Entertainment)
Mother pleads for baby's return
Toys withdrawn in E.coli health scare
Nurses role set to expand
(From Health)
Israeli PM's plane in accident
More lottery cash for grassroots
Pro-lifers plan shock launch
Double killer gets life
Cold 'cure' comes one step closer
(From Health)
Straw on trial over jury reform
(From UK Politics)
Tatchell calls for rights probe into Mugabe
Ex-spy stays out in the cold
Blair warns Livingstone
(From UK Politics)
Smear equipment `misses cancers'
(From Health)
Boyzone star gets in Christmas spirit
(From Entertainment)
Fake bubbly warning
Murder jury hears dead girl's diary
Germ warfare fiasco revealed
(From UK Politics)
Blair babe triggers tabloid frenzy
Tourists shot by mistake
A new look for News Online