About 10 children were at a 9th birthday party in Stretton Street, when parents and kids noticed a man carrying a sawn-off shotgun less than 100 metres away in a paddock off Nathan Street.

Sarah Nilson was hosting the party and said one of the kids came in from the street yelling: “He’s got a gun”.

The kids were rounded up into safety and away from windows and the police were called.

But it was the police response which has left Mrs Nilson, her husband Errol and Leonie Reading angered.

Mrs Nilson says she called Mount Isa Police at 4.13pm and had to make another phone call at 4.25pm before police arrived about 20 minutes after her initial call.

But Mount Isa Police Sergeant Brad Inskip said police had gathered the information and began searching the parameter of the paddocks within 20 minutes of the call.

“Based on the details provided that’s as far as the initial search went because the description was that the man had a gun, a sword or a stick and there was no other information,” he said.

Mrs Reading said the gunman told her to “sit the f--- down” and was “mouthing off at the children”.

The trio spotted the gunman later that day, and Mrs Nilson says she called police at 5.22pm but they didn’t attend her residence until about 6.30pm.

Sergeant Inskip said police had cordoned off the horse paddock and had all available police resources on scene with officers positioned tactically on the paddock boundaries within 35 minutes of the call.

Mrs Nilson said if police took the first call “seriously they would have caught him”.

“When you call 000 and tell them someone has a gun they should respond quickly and take it seriously,” she said.

Mrs Nilson said the kids were “stunned, hysterical and couldn’t breathe” after the ordeal.

Police received three separate reports of gunshots in the area later that night but could not locate the alleged gunman.

Sergeant Inskip said anyone with information can call the police station or Crime Stoppers.