Three people were arrested overnight on suspicion attempting to break in to Dudey Zoo after being spotted running through the castle ruins by a police helicopter.
Officers were sent to the scene after a 999 call was received from a member of the public whoâ€™d seen a group scaling a perimeter wall at around 12:50am.
The National Police Air Service (NPAS) was on scene within minutes scouring the 40-acre site and soon picked out the suspects using a heat-seeking camera.
Police on the ground were directed in and arrested a 22-year-old woman and two men, aged 24 and 26, on suspicion of attempted burglary. They remain in custody this morning.
No animals were hurt during the break-in and investigators are working to establish whether or not anything was taken by the intruders.
A spokesperson from Dudley Zoo said: “A neighbour alerted our security team who in turn contacted the police. The site has been fully checked and there are no signs of damage or access to enclosures.”