Four men have been arrested in and around London on suspicion of a planning an act of terrorism at the start of a busy weekend for the royal family and other dignitaries.
The arrests came two days before Remembrance Sunday, when a service is held at the Cenotaph memorial in central London attended by most of the royal family -- though specific targets of the alleged plot were not made public.
The queen and the royal family also are set to attend an event at the historic Royal Albert Hall in London tonight, part of a weekend full of public events the royals attend to remember the nation’s war dead.
Scotland Yard continued to question the men this morning after arresting them Friday in London and High Wycombe, outside of London.
Neither police nor the palace was directly linking the arrests to Remembrance Day weekend events.
However, the arrests were made during the day on Friday, not overnight as is usually the case, which suggested the operation was done in a hurry.
Security had already been heightened because of jihadis returning from the frontlines in Syria threatening to carry out attacks on British soil and the recent incident in which a gunman stormed Canada's parliament after shooting a military reservist at the Canadian national war memorial.
ABC News' Michael S. James contributed to this report.