This is the shocking moment that a woman cradling her four-year-old son stepped straight off a subway platform and plummeted on to the tracks.
The mother hurried into Kendall Station in Cambridge, Massachusetts, with the boy in her arms and fell on to the rails without seeing where she was going.
Horrified fellow passengers rushed to check if the pair were hurt and two bystanders jumped on to the tracks and lifted the mother and child to safety.
Joe Pesaturo, a spokesman for the Greater Boston transport system, MBTA, said: ‘The mother explained that she had seen a train at the northbound platform and believed she could board it.
‘She was looking straight ahead and apparently did not see the pit or the southbound tracks below.’
The woman and her son, who are from Attleboro, Massachusetts, did not suffer any visible injuries but were taken by ambulance to Mass General Hospital to be examined.
Mr Pesaturo added that ‘the mother was concerned that her son hit his head’, according to the Boston Herald.
The accident took place on Boston’s Red Line at 6pm on Wednesday, when the woman tumbled four foot from the concrete platform.
The man who scooped up the little boy and a female passenger who assisted the mother both got on the next train without leaving their names with staff.
‘I’ve never seen anything like this involving a mother and a child both falling into a pit,’ said Mr Pesaturo.
He said the mother, son and rescuers risked not only getting struck by an incoming train but also touching the third rail, which has 600 lethal volts running through it.
‘The bystanders quick response is worthy of praise, but it’s also important that the public remember that the subway’s third rail is electrified,’ he said. ‘It’s always best to immediately notify an MBTA employee so that we can alert nearby train crews and shut off the power to the third rail as soon as possible.’