"The fire is well involved but we have no reports of injuries, everyone has got off safely.
"We don't know how many were on the bus at this stage."
The crash closed all southbound lanes of the motorway for some time. All but one lane had been reopened by 11.30am, and the final lane reopened at midday.
"The bus has been moved to the shoulder while mechanics prepare it for removal. Motorists should take care while travelling in this area," police saaid.
"Lane one will close for a short period when the bus is removed."