Four men arrested in connection with an investigation into the attempted murder of Det Chief Insp John Caldwell in Omagh last week have been released.
Two others remain in custody after extensions to their detention periods were granted by a court in Belfast.
At least 10 shots were fired during the attack on Det Chief Insp Caldwell last Wednesday at a sports complex in Co Tyrone where he coached a youth football team.
As of Monday, his condition in hospital was described as critical but stable.
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On Tuesday night, the Police Service of Northern Ireland (PSNI) said four men, aged 22, 38, 43 and 45, had been released following questioning as their investigation continues.
Detectives have been granted further time to question a 47 year-old man after a Belfast court granted an extension to his detention until 10pm on Thursday.
Separately, a court granted an extension to the detention of a 71-year-old man until 10pm on Wednesday.
Both men remain in custody in the Serious Crime Suite at Musgrave Police Station.
Major investigation team detectives repeated their public appeal for help and have appealed to witnesses to make contact.
On Monday, police released CCTV footage of a blue Ford Fiesta, thought to have been used by the gunmen in the two weeks before the attack or in the immediate aftermath.
Det Chief Supt Eamonn Corrigan appealed to anyone who had seen the car in the two weeks before the attack to make contact.
The PSNI have said they believe the attack was terror-related, describing the New IRA as their primary line of inquiry.
