New Zealand issues tsunami warning after 5.9-magnitude quake; residents urged to evacuate to higher ground immediately.

Initially assessed as a magnitude-6.3 earthquake, NEMA later revised that downward to a 5.9.

More than 17,500 people reported feeling the shaking nationwide.

An earthquake of magnitude 6.3 struck near the town of Te Anau on New Zealand's South Island, prompting authorities to issue a tsunami warning.