A woman was reportedly dragged between the train and the tracks at the Clapham South London underground station during morning rush hour.
Eyewitnesses said the woman, believed to be in her twenties, reportedly got pushed under the train due to overcrowding, after her coat got stuck in the train doors as it was pulled away.
Transport for London (TFL), however, denied the incident occurred due to overcrowding.
Nigel Holness, London Underground's Operations Director, said: "Just before 8am this morning a passenger fell between the train and tracks at Clapham South station.
"The passenger has been recovered by the emergency services with non-life-threatening injuries. There was no service from Morden to Kennington for around an hour, while the rest of the line had minor delays. The service has now resumed."
Soon after the incident, commuters took to social media to express their shock after the incident resulted in huge delays and a shut down of services on the London Underground Northern Line between Kennington and Morden.
Two fire engines, a fire rescue unit and ambulances arrived at the Clapham South station and a "scoop stretcher" was used to eventually rescue the woman, said the The London Fire Brigade, reported The Independent.
The incident is not being treated as suspicious, though British Transport Police said investigations are on-going to determine "exactly what happened".
The incident has renewed calls for TFL to address the overcrowding, which saw commuters jumping over ticket barriers at London Bridge last week.
"This chaos must end now. The scenes at London Bridge were completely unacceptable," the Mayor of London had said following the London Bridge incident.
"It is a disgrace that Network Rail and the train operating companies have failed once again to get a grip of the situation at London Bridge."