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
Clear spells and showers overnight. Drier and brighter and a little warmer on Saturday. Rain and wind into Sunday morning
Higher risk of sunburn for the first part of the weekend with some late May sunshine
Your northwest pollen forecast for the next few days