An improvised explosive device today went off on a Tube train at a busy station in southwest London, leaving more than 18 people injured, in what Scotland Yard described as a "terrorist incident". <br/><br/>The incident occurred during rush hour in the morning on a District Line Tube train as it pulled into Parsons Green station. Scotland Yard has said an explosion caused by a suspected "bucket bomb" on a London Underground train at Parsons Green is being treated as a terrorist attack.<br/><br/>Assistant commissioner Mark Rowley said a suspected Improvised Explosive Device is thought to be responsible for the blast. He said more police would be deployed across London particularly on the transport network. He refused to say whether anyone had been arrested.<br/>Scotland Yard's counter-terrorism squad, SO15, arrived at the scene at Parsons Green Tube station and took the lead in the investigation from the British Transport Police.

An explosion on a London Underground train at a station in south-west London today left 18 people injured and caused panic in the area. <br/><br/>The city's District Line has been affected at Parsons Green station and several people are believed to have been hurt as a result of a large white plastic bucket in a supermarket plastic bag exploding in one of the carriages. Foreign Secretary Boris Johnson appealed for calm.<br/><br/>While the nature of the explosion is not yet known, Police bomb squads and fire crews have been rushed to the station along with ambulances.