Two further arrests have been made by detectives investigating the attempted murder of Detective Chief Inspector John Caldwell in Omagh.
Tonight marks a week since the suspected New IRA gun attack at a sports complex on the Killyclogher Road.
The PSNI officer remains critically ill, but stable, in hospital.
A 33-year-old man was arrested in Omagh, while a 57-year-old man was arrested in Belfast earlier today.
Both were arrested under the Terrorism Act.
Two men, aged 47 and 71, also arrested in connection with the attempted murder, remain in police custody at this time.
