The inquiry into the Manchester Arena bombing has been told that Greater Manchester Police "left after doing their bit" in terrorism training exercises held before the attack.
The inquiry is investigating the exercises that were held in the years before the attack on May 22, 2017, in which 22 people were killed and hundreds injured when a bomb was detonated in the foyer of Manchester Arena after a concert.
John Fletcher, who worked for 18 years on contingency planning for major incidents as group manager of the Greater Manchester Fire and Rescue Service, said the exercises were to test how well emergency services worked together.
Mr Fletcher said was disappointed that in the co-operation exercises, police officers disengaged after neutralising any threat, rather than helping fire and ambulance staff with casualties.
He told the inquiry that after an exercise in January 2014, he and his colleague at North West Ambulance Service had "strong words" with the police about their lack of co-operation.
But Mr Fletcher said the same thing happened at another exercise later that year.
He said the fire service had continued with that exercise and "refused to yield", so they could test their capabilities fully.
But Mr Fletcher said there were "quite a few" police officers "who weren't really paying attention to the elements we were doing".
He said that at a training exercise at the Trafford Centre in May 2016, the police inspector in the inner cordon would not allow fire and ambulance services inside, which caused a 90-minute delay in firefighters attending.
He said there was a general "lack of understanding" in what the fire service could provide.
A former police inspector then told the inquiry it had been clear long before the bombing that a probable point of failure in the event of a big terror attack would be the role of the force duty officer, because they had too much to do.
David Whittle, who conducted firearms training for 20 years, said the duty officer role was an "impossible task" and it would feel to the person fulfilling it "almost like being hit by a tidal wave".
But the inquiry heard that weeks before the bombing, Mr Whittle increased the number of tasks for the duty officer in the event of a terrorist firearms attack.
He said he had done so because those were "the duties that must be discharged" by the officer.
"That's not saying the FDO was responsible for doing all of them personally, but they are responsible for ensuring these things occur," Mr Whittle said.
There was no mention in the plan for who should help the duty officer to complete those duties, but it would be left to individual commanders to decide, he said.
The inquiry has previously heard that the police inspectorate warned in November 2016 that "an over-reliance" on the FDO could see them overwhelmed.