Those injured have been flown to hospital.
The public is asked to avoid the area.
The earthquake was 38km deep.
Police shot the loose horses dead after they posed a risk to the public.
Police described the man as "agitated and armed" during the incident.
Officers have found his vehicle and gun but believe he is still armed.
Schools announced the lockdown was over and parents could collect their children on social media.
The highway is blocked north of Tūrangi and motorists are urged to avoid the area.
The highway near Waitahanui has closed as a result of the crash.
