"Apparently the back of his bag was caught in the door, and the driver hadn't noticed it.''
It was not yet clear whether the boy managed to remove his bag or whether the bus stopped.
Mr Strickland said the boy suffered minor to moderate gravel rash across his body, with most of the injuries on his buttocks.
"It would be sore, but he was a brave little man. No crying at all, and fully conscious and talking to us about the whole situation.''
He and his mother had been quite calm.
Mr Strickland said he was glad the incident was not more serious.
"It could have gone both ways, you never know.''
The boy attends the year one-eight Huiakama School, which has 10 pupils.
Principal Vivienne Wallace did not see the accident and had few details about it.
However, the other children did not seem to have been affected, she said.
"They don't seem to even have noticed.''