TIU detectives also conducted a number of searches in Strabane on Friday evening, November 18.
Three men, two aged 36, and a 28-year-old have been arrested Section 41 of the Terrorism Act.
They have been taken to the Serious Crime Suite at Musgrave Police Station.
More than 1,000 residents were affected by the security alert, with children being unable to get to school and carers unable to reach vulnerable residents, politicians say.
While no homes were evacuated, the road into the residential area was closed for much of Friday.
The road has since reopened.
The attempted murder investigation continues and police are appealing to anyone with information to contact them on 101.
Additionally, information and media can be provided to police through the Major Incident Public Portal link: https://mipp.police.uk/operation/PSNI22A02-PO1
Information can also be provided to Crimestoppers anonymously on 0800 555 111 or online at: www.crimestoppers-uk.org
Chief Constable Simon Byrne and Assistant Chief Constable Bobby Singleton visited Strabane on Friday to show support for local officers.
Assistant Chief Constable Singleton said: “Our thoughts are first and foremost with the two police officers who were here last night serving their community.
“Fortunately they are left simply shaken by what happened last night, but we are treating this incident as a credible attempt to murder those officers. This is an attempted murder investigation.
He also acknowledged the local community, saying: “We have somewhere in the region of 1,000 residents who have been affected by that security alert.
“We take this opportunity to thank them for their patience.”
Tags: