It is understood the two armed robbers shot by gardaí in Co Dublin yesterday were fired on after they failed to drop their weapons despite repeated requests to do so.
Garda sources say one of the men, 33-year-old Colm Griffin, pointed a loaded handgun at gardaí outside Lusk Post Office and that this has been captured on CCTV.
Post mortem examinations carried out last night found that Mr Griffin and 24-year-old Eric Hopkins died after they were both shot once in the upper body.
The garda inquiry into the shootings is now under way. Amnesty International is demanding an independent investigation into the killings.
A number of staff who were in the shop at the time have told investigators that they heard the men being shouted at repeatedly to drop their weapons before they were shot.
Members of the Emergency Response Unit also tried to resuscitate the two men at the scene and succeeded in reviving one of them, but he later died in hospital.
Garda operation criticised
Meanwhile, the owner of the shop which houses the post office, Eugene Larkin, has claimed his staff were left exposed by gardaí and has demanded an explanation from them.
Mr Larkin said that while post office staff were made aware that a raid was about to take place his staff were not told anything.
He said the raiders gained entrance through the back door. One of them put a gun to the face of his manager telling her, other staff and customers to lie on the ground.
He noted that the raiders were able to survey the premises and realised there was a back entrance into the shop and questioned why gardaí and the surveillance team had not done the same.
In response, Superintendent Kevin Donoghue said operations of this kind were hugely sensitive and it was important to keep details secret.
He said there was good reason to adopt the plan that was put in place yesterday.
Offer of counselling
The two gardaí who fired the fatal shots have been offered counselling, as have all the staff in the shop who witnessed the incident.
Garda Commissioner Noel Conroy has issued a statement saying the gardaí regrets the loss of life in any circumstances and conveys its condolences to both families.
The three other raiders and one woman, a girlfriend of one of the men, are still being questioned about the incident.