A police helicopter was launched in an unsuccessful bid to help catch lead thieves who were seen on a roof.
Officers were called at just after midnight on Monday, January 20, by a dog walker who saw two people on top of Ryelands House on Owen Road in Lancaster.
Lancashire Police said the offenders were seen removing roofing lead and the area was cordoned off.
A fire service cherry picker was brought in so police could check the roof.
The search confirmed that lead had been taken from the building but the suspects fled on foot across the park.
Officers gave chase and police dogs were also brought in, however the suspects could not be located.
A spokeswoman for Lancashire Police: “They were pursued by officers into Skerton High School grounds but, despite use of the helicopter and the dog patrol, the offenders were not found.”
Inquiries into the incident are continuing.
Anyone with information about the incident is asked to contact police on 101 or Crimestoppers anonymously on 0800 555 111.