Seven Greek schoolchildren were killed when the bus bringing them to the Paralympic Games crashed into a truck near the central town of Kamena Vourla.
Between 20 and 30 other children were slightly injured. One child and one adult escort had more serious injuries, but none was said to be in danger. All were admitted to a hospital in the nearby city of Lamia.
The bus was carrying nearly 40 15-year-olds and four teachers from the city of Trikala in central Greece.
According to media reports citing police sources, the truck swerved into the motorway bus lane, possibly after one of its tyres burst.
The drivers of the two vehicles were not injured and were held at a local police station to testify.
