Thameslink services experience major disruption at London St Pancras after an incident that emergency services are dealing with. Multiple reports say trains are not operating in or out of St Pancras for the remainder of the evening, indicating a temporary suspension of service through the station. The disruption affects passengers using Thameslink routes that normally run through St Pancras, with no immediate update reported on an earlier resumption time. Authorities and transport updates are referenced as the reason for the cessation of trains, with emergency services responding to the situation. The reports consistently describe the disruption as significant and ongoing for the evening, rather than a short interruption. Passengers are advised to expect delays and seek alternative travel options until services resume. Further details about the incident are not provided in the available summaries.