WELLINGTON, Sept 3 (Reuters) - New Zealand"s third largest internet provider Vocus NZ said on Friday its response to a cyberattack temporary triggered a widespread internet outage. The company said its systems blocked a denial of service (DDoS) attack on one user but in doing so caused some Vocus customers in the country"s largest cities - Auckland, Wellington and Christchurch - to suffer outages. Vocus said the issue was resolved within 30 minutes. "We are working closely with the vendor of this platform to understand why this occurred," said a company spokesperson. A DDoS attack is a way in which hackers disrupt a server by overwhelming it with a flood of internet traffic.