A pedestrian was killed and 18 passengers were injured, four seriously, when a London double-decker bus crashed into a tree on a route in the city centre, police said Tuesday, according to dpa. The woman who was killed was believed to have been walking along the pavement when the incident happened near Tower Bridge in central London. One witness said the collision was caused by a large tree branch which smashed into the double decker. Nine people were taken to hospital, four of whom suffered serious head and neck injuries, police said. Others were treated at the scene. Pictures showed the windscreen on the upper deck of the bus demolished.