Two seven-year-old children have been airlifted to hospital after a crash that involved four cars, police have said.
It happened at about 10:15 GMT on the A174 near Yearby in Redcar.
The two children – a boy and a girl – were taken to James Cook University Hospital in Middlesbrough.
Cleveland Police said a number of other casualties had also been taken to hospital and the A174 remained closed for a number of hours.
A spokesman for the Great North Air Ambulance Service said the boy had leg and head injuries.
