title: UK transport police leading investigation of London incident, counter-terrorism police aware
text: LONDON (Reuters) - British counter-terrorism police were monitoring events after media reports of a blast on a train in Parsons Green station in west London on Friday, but the investigation into the incident is being led by transport police, a security source said. Armed police rushed to an incident at a London underground station on Friday with local media reporting there had been an explosion on a packed rush-hour commuter train. Counter-terrorism officers were on the scene of the incident.  