Early on, there had been confusion around what happened in the explosions Police changed what they thought the timings of the tube blasts as they learnt more: the earliest reports had suggested that they happened during a period of almost half an hour. This was due to early confusion at London Underground (LU), where the explosions were originally believed to have been caused by power surges. An early report, made in the first few minutes after the explosions, involved a person under a train, while another described a derailment (both of which did happen, but only as a result of the explosions). A code amber alert was declared by LU at 9:19am, and LU began to stop the network's operations, ordering trains to continue only to the next station and stopping all services.