A screenshot of a previous mobile alert test. Photo: Supplied
The Director of the National Emergency Management Agency says tonight's nationwide test of the Emergency Mobile Alert System was a success.
The alert went out around 6.15pm.
John Price said well above 90 percent of people across the country received the alert.
"We were able to successfully transmit to all parts of New Zealand with cellphone reception.
"Five to six million cellphones were activated through that alert."
Price said people who did not receive the alert message may have been outside of cellphone coverage areas, or may have had their phones off.
He said he is aware of the government working with telecommunications companies to improve coverage in certain areas.
People began reporting receiving the alert shortly after 6.15pm.
Minister for Emergency Management Kieran McAnulty said it was a tool that can alert people when their life, health, or property was in danger.
He said when the alert sounds, people should stop and read the message and take it seriously.
Tonight's test is the fifth annual test.