One person died and 15 were injured in a crash involving two buses and a car in south-east London.
The driver of the car has been arrested over the collision on Sevenoaks Road in Orpington, on Thursday night.
One person was pronounced dead at the scene and 15 people had been taken to hospital, London Ambulance Service said. Three have serious injuries.
The arrested man was detained on suspicion of causing death by dangerous driving, the Met said.
The London Fire Brigade (LFB) sent 60 firefighters to the scene of the collision, which took place at about 22:15 GMT.
Resident, Tariq Sheik said he heard “an awful lot of ambulance and fire engine noises last night” and thought it might have been connected to Halloween.
“Horrific scenes, it’s not very pleasant,” he added.
Several people were rescued from the single-decker buses, helped carry out first aid and made the vehicles safe, according to LFB Assistant Commissioner Graham Ellis.
Road closures are in place around the area and police have advised motorists to use alternative routes.
Six bus routes have also been diverted.