One child has been taken by ambulance to the Royal Children's Hospital and 10 others to local hospitals, however, a Victoria Police spokeswoman said it was not believed anyone received serious injuries.

The spokeswoman said the bus, which was carrying 47 students from Euroa Secondary College, collided with the truck after turning onto the Hume Freeway from Alexandersons Road about 8.30am.

Investigators were told a truck travelling in the left lane of the freeway attempted to merge and misjudged the manoeuvre, hitting the rear of the bus.

Both vehicles ran off the road.

Euroa Secondary College principal Scott Watson said 17 students were assessed by paramedics at the scene.

Mr Watson said the injured students were suffering from varying degrees of whip lash, and the majority of those who had been hospitalised were back at home with their families by lunch time.

"We certainly are relieved that no students were seriously injured," he said.

"Going forward, we've got counsellors on site today and tomorrow, and in the weeks to come should the kids need to speak to someone about what's happened this morning."

The 51-year-old truck driver from New South Wales was uninjured and is helping police.

Mr Watson said as far as he was aware the bus driver was also uninjured.

Country Fire Authority crews and the State Emergency Service also attended the scene.

The road between Locksley and Longwood was cleared by 2pm, police said.

Anyone who witnessed the collision can contact Crime Stoppers on 1800 333 000.