A 31-year-old man was arrested from a house in Chesterfield, Derbyshire, while three others, aged 22, 36 and 41, were arrested in three separate properties in Sheffield, South Yorkshire. They were detained by officers from the north-east counter-terrorism unit (Nectu) and are being questioned at a police station in West Yorkshire. The arrested are suspected of Islamist-links.
The arrests were intelligence-led and planned as part of an ongoing investigation, police were quoted as saying by The Guardian.
In this regard, the army's bomb disposal unit was called to the Chesterfield house where one of the arrests was made.
"I understand our local communities will have concerns about this morning's police activity but I want to offer my reassurance that we will continue to serve and protect the public of South Yorkshire," Supt Una Jennings of South Yorkshire police said.
The residents in the area were jolted awake by the sounds of the army bomb squad breaking into the property. The immediate area surrounding the property was also evacuated and cordoned off during the search operation.
Raids were conducted in properties of Sheffield as well.
British officials are on their toes after five terror attacks escaped detection.