Watch: 'It was a miracle' - intensive care paramedic describes difficult Waitakere rescue operation

Auckland Westpac Rescue Helicopter intensive care paramedic Russell Clark has described the moment he was winched down to one of three boys who survived a tragic accident in a swollen river in Auckland's Waitakere Ranges yesterday.

Auckland Westpac Rescue Helicopter crewman Russell 'Rusty' Clark says survivors were lucky to escape a swollen river. Source: 1 NEWS

Two teenage boys lost their lives after they were swept away in flash flooding as a group of five boys were swimming near the Cascade Falls.

Spotted by the crew on board, it was clear to Mr Clark that one of the boys was waist deep in the water and could not go anywhere due to water and debris flowing either side of him.

Not a common kind of mission, and one that was a real risk, the helicopter crew made a quick call to make the rescue as darkness begun to fall.

Winched down by his fellow crew, Mr Clark threw a strop over the boy and said he would not let him go for anything. 

Two teenage boys swimming with three others were swept away and drowned. Source: 1 NEWS

"I got the feeling he knew how close he was to dying," he told 1 NEWS. 

Whilst it is part of their job to remain professional and hold back emotion, he said there was a real sense of relief when they made it back to the helicopter.

Mr Clark praised his fellow helicopter crew members, saying it was a miracle they were able to spot the boy so quickly considering the weather conditions.

Mr Clark was also part of the crew who attended the rescue mission on Manukau Harbour where a person fatally drowned today. 

The weekend tragedies are an awful reminder of the dangers of unpredictable weather and how quickly conditions can change.