FAIRFORD, England (Diya TV) — British police said Monday they were releasing five men on bail after arresting them near RAF Fairford on suspicion of explosives offenses and preparing a terrorist act. Counterterrorism officers are examining whether anyone acted on behalf of a foreign state, but they have not established a motive or announced charges.

Police received a call at about 12:45 a.m. Sunday reporting three suspicious vehicles that appeared to be heading toward the airbase in Gloucestershire. Armed officers responded and arrested the men in nearby Whelford. Police later added suspicion of preparing a terrorist act to the initial explosives-related arrests.

The men are British nationals, ages 23 to 25, who live in London. Police have not released their names. Investigators examined the three vehicles overnight with help from military personnel and forensic specialists. Authorities placed a cordon around the scene and evacuated about 85 households while the Army’s bomb-disposal unit carried out its examination.

Assistant Commissioner Laurence Taylor, head of Counter Terrorism Policing, said officers had interviewed the men and would release them under conditions restricting their movements and contact with others. He said all five remain under investigation. The cordon was still in place when police issued their Monday afternoon update, although Taylor said officers hoped to reduce it and allow residents to return home.

Taylor said investigators were pursuing several lines of inquiry, including whether individuals knowingly or unknowingly worked for a foreign state. He did not identify a country or say police had established such a connection. Officers are also trying to determine what the men knew and why they were near the base.

RAF Fairford is used by U.S. forces, including bombers involved in operations against Iran. That role has drawn attention to a possible Iran connection, but police have not linked the country to the arrests. They also have not said whether investigators found explosives in the vehicles.

Police said the investigation is continuing and asked anyone with information about the vehicles or activity near the base to contact counterterrorism officers.