British authorities are investigating how an intruder breached the walls of the Tower of London and stole a set of keys from the tourist attraction and home of the crown jewels – the crowns and scepters used by Queen Elizabeth II on ceremonial occasions.

According to an article from Reuters, the stolen keys did not provide access to the Tower itself. Locks to the Tower’s drawbridge, conference rooms and a restaurant (the keys stolen by the burglar) have all been changed.

The burglar was reportedly spotted by the Yeoman Warders, Tower guards commonly known as the “Beefeaters,” but the guards did not leave their posts to stop him, instead radioing for help, ABC News reports.

The burglar made it all the way to the gate at the main entrance before being apprehended.

While the intruder did not at any point gain access into the Tower or get near the crown jewels themselves, Historic Royal Palaces is acknowledging that procedures were, in this instance, “not carried out to the expected standard,” and they are pursuing a “staff disciplinary procedure,” ABC reports.