Passengers smashed their mode retired of a conduit bid successful southbound London pursuing a occurrence alert connected Friday evening.
The northbound bid was stopped astatine Clapham Common presumption astatine astir 17:50 BST erstwhile radical were seen smashing the train's windows and climbing out.
A spokesperson for Transport for London (TfL) said: "We're atrocious for the distress caused astatine Clapham Common."
The London Underground relation confirmed connected societal media that determination had been a occurrence alert astatine the station.
There were terrible delays connected the Northern Line arsenic a effect of the incident, TfL said.
The spokesperson added: "The London Fire Brigade attended the presumption and confirmed determination was nary fire.
"We are investigating the details of this incident."
One rider astatine the presumption told BBC London: "We were each stuck wrong the Tube with locked doors. We could perceive radical astatine the different extremity of the Tube screaming and banging connected the doors and windows to get retired of conduit carriages.
"We had nary thought what was going on. People connected the level and successful the Tube were smashing done the windows to get out. I present realise that's due to the fact that the Tube carriages were filling with smoke."
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