The senior officer shot in Omagh has been named as Detective Chief Inspector John Caldwell as police said the primary focus of the investigation is on dissident republicans.

Three men have been arrested in Northern Ireland in connection with the attempted murder of an off-duty police officer who was shot several times.

Gunmen shot Detective Chief Inspector John Caldwell in front of his young son in the attack at a sports complex in Omagh, Co Tyrone, on Wednesday evening.