According to a statement from Network Rail, tens of thousands of passengers were affected, "as a result of the failure of TfL infrastructure outside Liverpool Street station on the evening of Wednesday 28th May."
Commenting on the incident, Network Rail's Director of Operations and Customer Service, Robin Gisby, said: "Passengers rightly want an explanation, as do I. Passengers deserve an apology for the disruption they suffered last night and this morning and I want assurances that such an incident can't and won't happen again."
Network Rail said a concrete slab fell onto rail tracks at around 7.15pm last night. A TfL spokesperson told NCE that this was due to a jack malfunction, and the bridge falling suddenly from its jacked position to its final position.
The bridge, known as GE19, was erected by a Balfour Beatty/Carillion joint venture over the May Day bank holiday as part of TfL's ongoing project to extend the East London line.
Services were stopped as a result of the incident, resuming at 0930 this morning when TfL gave the 'all clear' and services were allowed to re-start.
Network Rail have, "concerns over TfL's handling and management of both the project and its contractors," reads a statement,
"Network Rail has banned work on the bridge, effective immediately. This will remain in place until TfL has completed an investigation and reported back on the causes of the incident and what measures it will be putting in place to prevent a repetition," it reads.