A bus had its entire roof sliced off after crashing into a Dumbarton railway bridge leaving debris strewn across the street.
The First Bus vehicle was ripped apart during the shock incident on Townsend Road in the town centre.
Self employed carpenter and builder, Jack Hanlon, arrived on the scene shortly after the crash happened.
The tradesman, from Helensburgh, said: “It must have happened at about 7am.
“The bus was a right mess but it didn’t look like anyone was on board which was lucky.”
First Bus confirmed they are investigating the incident.
A spokesperson said: "We can confirm an out of service bus has been involved in an incident on Townsend Road, Dumbarton this morning.
“There are no reported injuries from anybody on-board at the time or members of the public.
“Emergency services attended the scene and the bus is in the process of being recovered.
“The safety and well-being of our passengers, drivers and the public are our number one priority and we are conducting a full investigation to determine how this incident happened.”
