One person has died and another is critically injured after a serious crash between a truck and two cyclists in the South Island this morning. St John Ambulance confirmed one cyclist died at the scene, and another was flown to Christchurch Hospital in a critical condition. No one else was injured in the crash. Police say the 6.20am crash happened on the Tekapo-Twizel Rd near the Mt Cook turnoff. Motorists are being advised to avoid State Highway 8 in Pukaki and to expect delays. The road has now been closed between Twizel and the Mt Cook Rd turnoff.