Eighteen commuters were injured today when the entire roof of a double-decker bus was torn off after it hit a tree.
Seven people were taken to hospital after police, ambulance and fire services were called to the accident on Fishponds Road, Bristol, at 7.40am.
The accident involved the 342 First Bus service that was travelling down the busy main road when it hit the low hanging tree branch.
Those injured had been travelling on the upper level of the double decker. The ripped-off roof landed 100 yards further down the road from where the bus came to a stop.
Jonathan Pomeyie told the BBC he was at the back of his house making a cup of tea when he heard a loud bang.
"It was a very deep impact type of sound, like an explosion.
"I saw police, paramedics and firemen everywhere. It was a horrid and unbelievable sight to wake up to."
Ambulance crews, including doctors with specialist trauma training, treated seven passengers who were taken to hospitals in the area.
Although none were believed to be suffering life threatening injuries, a man in his twenties, who had been trapped in the bus, was taken to Frenchay Hospital with a suspected back injury.
Eleven people were treated at the scene, near the junction with Alcove Road, with patients suffering cuts and bruises to their heads.
All of those treated were adults with no children involved in the accident, a spokesman for the Great Western Ambulance Service said.
The bus driver was not injured.
Great Western Ambulance Service officer at the scene Dave Manners said: "This incident obviously had the potential to be much worse but luckily none of the patients suffered life-threatening injuries.
"In an incident such as this with so many patients, it is essential that we are able to use all of the specialities within our service, treating people and providing care at the road-side without the need for a trip to hospital."
A spokeswoman for First Group said: "We can confirm that there has been an incident this morning on Fishponds Road involving a Service 342 bus.
"The top of the double decker bus was in collision with some tree branches which were hanging over the road."
She added an investigation into the exact causes of the incident is now under way.
"Our teams are working closely with the relevant authorities on this to ensure that all the possible contributing factors are considered," she said.
"We are also working with the police to obtain the details for all those who were involved in the incident this morning.
"We will endeavour to contact those involved to find out how they are and to gather additional information about what happened in order to assist with our investigation."
A spokeswoman for Avon and Somerset police said the road was closed for much of the morning from the Eastville side of Hawkesbury Road and also the Fishponds Road junction with Brentry Road.
Motorists were urged to avoid the area while the road was cleared. It re-opened shortly before midday.