Police are continuing to search scenes in Burngreave and Chesterfield for a second day, after four men from South Yorkshire and Derbyshire were arrested on suspicion of terrorism offences.
Officers are searching the yard and outside area of the Fatima Community Centre in Burngreave.
They have been using a drone to take aerial videos of the site.
The Army Bomb Disposal Unit has carried out a controlled explosion of material found at a chip shop in Chesterfield.
Counter terrorism officers can hold four men being questioned on suspicion of terror offences until 4pm on the afternoon of Christmas Day
Armed police have swooped on a number of properties in Derbyshire and Yorkshire in an operation to foil a "suspected Christmas terror plot".