Emergency call centre staff who were on the phone to people clinging to roof tops in fear of their lives during Cyclone Gabrielle are still traumatsied by what they heard.

In the 12 hours where Gabrielle unleashed her worst on the upper North Island, the 111 call centre recieved more than five times its usual volume of calls for help.

NZ Professional Firefighters' Union representative, Carlos Dempsey is a 111 call-taker and team leader. He said the callers were desperate.

In a statement to Checkpoint, FENZ national Commander Russell Wood said the weather conditions, the level of flooding, and sometimes their own circumstances, meant people couldn't reach many of those in need on the night.

"The number of calls far exceeded our people's capacity to respond to them all and the conditions prevented our people reaching many of the calls we were able to respond to.

"Helicopters were unable to rescue people in darkness and due to the overnight weather conditions and rescue efforts continued to be hampered during the following day due to high winds.

"Firefighters did an amazing job in the circumstances. There will be an operational review into our response including how we responded to 111 calls, but at the moment our focus is on the immediate response and recovery effort."