Three crew members have died after their Royal New Zealand Air Force helicopter crashed into a hill near Wellington on Sunday morning. They were killed in the crash and a fourth crew member is in hospital in a critical condition. Authorities are now trying to work out exactly how the helicopter crashed.<br/> <br/>The Iriquois helicopter was one of three on its way from the Ohakea air base to Wellington to take part in fly overs as part of Anzac Day services. <br/> <br/>The helicopter was flying in heavy fog and crashed into the Paekakariki hill, 40 kilometres north of the capital. <br/> <br/>Details about who was on board have not been released.<br/>