More than 30 people have been injured, seven of them seriously, in a bus crash in south London.
Two passengers who were trapped on the double-decker bus in Kennington had to be freed, London Fire Brigade said.
The number 59, heading to King's Cross, swerved to avoid a vehicle and hit a tree near the Ship pub on Kennington Road, said Transport for London.
Fire crews, paramedics, the air ambulance and officers from the Metropolitan Police went to the scene.
London Ambulance Service said it treated 32 patients in total.
Twenty-five people were "walking wounded" with cuts and bruises.
The more seriously hurt had mostly head and leg injuries.
A man and a woman who were trapped in the bus also had serious leg injuries.
Transport for London said the bus swerved to avoid hitting another vehicle
Jesse Fox, an actor from north London, was on the top deck of the bus when it crashed, pinning the two passengers in their seats.
Clive Robinson, London Fire Brigade: "Crews on arrival
found a very challenging incident"
"We were going along at a fairly normal speed and I heard people shout and I could see out of my right hand window that it was swerving to avoid a car," he said.
"Then I heard people shout a lot louder and looked up and literally saw this tree crash through the front of the bus.
"Most people on the top deck were fine, but for the people at the front it looked pretty bad."
The BBC's Rebecca Cafe, who went to the scene, said the two trapped people had been freed by emergency services.
Transport for London's director for buses Mike Weston said: "Our first concern is, of course, for the driver, passengers and others involved in this incident and we can confirm the emergency services are in attendance.
Two people were trapped in their seats at the front of the top deck, said another passenger
"There will be a thorough investigation into this incident as a matter of urgency."
London Fire Brigade station manager Clive Robinson said: "Our crews on arrival found a very challenging incident. We had people injured on both floors of the bus.
"We moved one lady from the ground floor who was injured, we moved people from the top floor using ladders and the back door on the bus.
"We've used hydraulic cutting equipment to release two people who were trapped.
"In addition, the floor of the bus was starting to collapse and we had to shore that up using hydraulic equipment to get the people upstairs out safely."