British police are investigating a burglary on the Windsor Castle estate, fueling concerns about security at the royal residence west of London.

The intruders entered a farm building on the castle estate last month and stole an Isuzu pickup and a quad bike, according to the local police.

The royal family is not immune to being the victim of crime. Law enforcement officials in England said that someone burglarized property on the grounds of Windsor Castle. The incident, according to the Thames Valley Police, happened just before midnight on Oct. 13, The New York Times reported.