There was an accident where an 81 year old man fell backwards when he pushed the end of the wheel chair he was riding onto the escalator.
I'm a bit confused by the part in bold. Does this mean that the man got out of the wheel chair and pushed it onto the escalator and then stood behind it? Or, can 押す be used to refer to the action of driving the wheel chair, i.e. he remained seated in the wheel chair and pushed it onto the escalator using the wheels?