Police say ten passengers were on the TransPeak bus at the time of the collision in George's Road.
One man was briefly trapped on the top deck before he was rescued by firefighters.
Three women and three men were taken to hospital for treatment to cuts and bruises.
The bus driver was not injured.
"It is only by sheer luck that no-one was seriously injured.
"If you were in the area at the time of the crash and witnessed the incident I would urge you to contact the police with any information."
More top news
Ian Brady has been refused permission to launch a High Court fight for the right to have his choice of lawyer at a tribunal
An ex-rock star says he has finally been cleared of any involvement in a Spanish murder after a 25-year nightmare.
A lifelong Manchester United fan popped the question to the girl who has the season ticket next to his.