Reports on social media suggest that a bag 'exploded' on a District Line Tube train at Pasons Green station.
The Met Police confirmed that they were aware of an 'incident' at Parsons Green Tube station and said officers were in attendance.
British Transport Police have revealed that the station is now closed and witnesses have reported seeing armed police in the area.
London Ambulance Service and London Fire Brigade are also attending the incident.
Pictures appeared to show an explosion in a bucket towards the rear of a train with passengers reportedly suffering 'facial burns'.