Children seriously injured in Melbourne bus crash

© Melanie Foster/AAP PHOTOS Police say the bus was carrying up to 45 children before the crash at an intersection in Eynesbury.

Several children have been seriously injured after a bus collided with a truck and rolled onto its side in Melbourne's west.

The bus was carrying up to 45 children at the intersection of Exford Road and Murphys Road at Eynesbury about 3.40pm on Tuesday, Victoria Police said.

Police initially reported up to eight children sustained serious injuries in the crash, before Ambulance Victoria said six patients were taken to hospital with "serious traumatic injuries".

Another 16 patients were taken to hospital in a stable condition. 

Among the 22 people hospitalised were 21 school-aged children and one adult, Ambulance Victoria said.

Paramedics were assessing another 25 people at the scene who did not appear to need hospital treatment.

Students from the nearby Exford Primary School were reportedly involved in the crash.

The male driver of the bus sustained minor injuries in the incident, while police were also speaking with the male driver of the truck.

The Country Fire Authority earlier said about six children were trapped as a result of the crash.

Major Collision Investigation unit detectives were deployed to the scene, with police urging anyone with information about the incident to come forward.