A double-decker bus driver has been taken to hospital, and two passengers are trapped on the upper deck after the vehicle crashed into a shop in a busy London high street.
Police were called just before 7am to reports of a bus hitting a building in Lavender Hill, near Clapham Junction railway station in south-west London.
A Transport for London spokeswoman said a route 77 double-decker was involved in the incident.
Police said there were no life-threatening or life-changing injuries.
Photos on social media show the vehicle on the pavement and smashed into the front of the Poggen Pohl Kitchen Design Centre.
Glass lay shattered across the ground and paramedics could be seen tending to people on the top deck.
Firefighters with cutting gear appeared to be trying to cut trapped passengers free from the top of the bus.
Police said paramedics had treated "a number of passengers".
Local resident Brendan Pfahlert said the smash "sounded like a large amount of glass being dropped".
Wandsworth Police tweeted: "Road will be closed for sometime, we have reports of casualties unable to confirm severity at this time."
The bus involved was the number 77 travelling towards London Waterloo.
Andrew Matthews, 34, of Wandsworth Town, said he was one of around a dozen passengers on the bus.
He told the Press Association: "I was on the top floor at the back, fortunately.
"I noticed the bus drifting. I heard a smash and saw the roof of the shop going through (the bus) from the front left. It went to the fourth or fifth row.
"I wedged myself in, bracing myself.
"As soon as the bus came to a stop there was yelling, screaming.
"I noticed a lady wedged in the front right-hand side. She was screaming for help. There was a lot of blood."
Nurse Amy Mullineux, 40, of Wandsworth Common, was also on the bus and said the driver told her he had lost consciousness before the crash.
"I spoke to him. He said he blacked out before the bus hit the shop.
"He doesn't remember hitting anything.
"The paramedic told me they think he had some kind of fit."
Witnesses reported seeing smoke coming from under the bus.
Solange Morin, 33, lives close to the scene and was hoping to catch the bus before she saw it crash.
She said: "I saw this woman (in the bus) shouting and banging on the glass.
"Everybody shouted 'fire, fire'.
"I went on to the bus. I talked to her and was holding her hands.
"She was pinned. I wouldn't have been able to get her out.
"She was so scared because people were shouting fire. There was a lot of smoke."