One person injured in Friday's terror attack has been discharged, but four are still in hospital.

Seven people were hurt at New Lynn Countdown, with at least five stabbed by ISIS supporter Ahamed Aathil Mohamed Samsudeen.

The person who was at Middlemore Hospital is now recovering at home.

Three others are in a critical but stable condition at Auckland City Hospital.

Another person is stable at the same hospital.

Security Review

Security services are taking another look at 30 to 40 people on a watch list, following Friday's terror attack in Auckland.

Samsudeen had been under 24/7 police surveillance since mid July, after being released from prison.

Security services are reviewing potential threats posed by others who may be inspired by the attack.

They're expected to check resources and warrants for surveillance are aimed in the right place.

Police Commissioner Andrew Coster says the public shouldn't be too concerned about heightened risk, because the event's an outlier and police aren't looking for anyone else.

Possible Mental Health Issues

Samsudeen's family say he was suffering from mental health problems.

His identity was revealed late last night, as the man responsible.

His family says they are heartbroken by this terrible event and would like to send their love and support to those who are hurt.

They say Samsudeen suffered during political torture in Sri Lanka, was assaulted in prison in this country, and spent too much time online, trying to impress his friends from Sri Lanka.