The Ministry of Education has confirmed they are aware of six threats made to North Island schools today.

Some schools in Gisborne, Waikato and Thames-Coromandel went into lockdown or were evacuated after threats were made, police said.

Ministry of Education central region hautū (leader) Jocelyn Mikaere said they had been notified of threats made by phone to five Waikato schoos and one Gisborne school.

"Our teams are in contact with all of the schools and will are prepared provide whatever support is needed."

Police were on site at the schools, which had immediately initiated their emergency management plans, Mikaere said.

Matamata Intermediate reported about noon that police advised the school to remain in lockdown and students at Matamata College were evacuated. Thames High School and Cambridge High were also evacuated.

Firth Primary School was in lockdown, but just before 1pm advised parents it was safe to pick up their children. Matamata Intermediate told parents about the same time they too could collect their children.

About 1.30pm, Thames High said students could go home if they were collected by a parent or guardian.

A teacher at a kohanga near Matamata College earlier said they had not been advised to go into lockdown but had done so out of concern. They said five police cars were parked at the front entrance of the school. Earlier they said they saw police with dogs.

Gisborne's Lytton High School said it too had received a bomb threat via phone.

"The police have been informed and are on site. All staff and students have been evacuated from buildings," the school said.

"The police have asked us all to remain on-site for now."

A police spokesperson said they were liaising with schools and investigating. They searched buildings at some of the schools.

"Police are aware of threats made via phone in relation to several North Island schools," they said.

Cambridge High School said in a Facebook post: "Due to a possible threat to the school, our students have been evacuated to the field. On the advice of the police we are going to evacuate from the school campus.

"Students will not have access to their bags and may be collected from Taylor Street. Those who can walk home are encouraged to do so.

"Bus students will be supervised off the school campus until the usual bus time. The bus company has been contacted, and we have made arrangements for buses to pick students up from Taylor Street at the usual time.

"Supervision is available for any student who cannot walk home or be collected before the end of the school day.

"All students and staff are safe, well and calm. The school reception and the student office cannot take calls at this time."

In an update to parents via Facebook, Cambridge High School said some students may have left their cellphones in class and would need to find another way to contact their parents.

"Some students who normally caught the bus home may have walked to friends' homes while other bus students had gathered on a field where they could then be collected by their parents."

Matamata Intermediate confirmed via social media just before midday it was "following police guidance" because of an "incident in the vicinity of the school".

Parents of pupils at Thames High School received a message from the school saying: "Following police advice, we have gone into lockdown for what is believed to be a low-risk threat at the school. Following police advice we are now moving into an evacuation so that police can check the interior of the buildings. We will update you when we have more information."

They later said it was a "low-risk bomb threat".

Matamata College said: "This message is to let you know that the school has received a threat and out of an abundance of caution, we have evacuated under police guidance. The police are continuing to investigate. There is no need to panic. Please do not come to the school. Further communication will be sent out as soon as possible."

They later added: "The police are still searching the buildings, which could take some time. Students who have parents who can collect them now are able to do so. However, we need to ensure they are collected by their parents. If you are wanting to collect your child please meet the staff wearing high vis vests on Station Road by the field. Please do not come onto the school grounds. We will bring students to you once you have spoken to a staff member. All students who drove themselves, who catch buses, or who rode bikes or walked to school need to remain, unless a parent can pick them up or until further notice. Please be patient."

Firth Primary School posted just before 1pm that "we have been advised by the police that it is safe for you to collect your child from school. You must come to the Station Road entry to school only and wait at the office and your child will be safely delivered to the office.

"We can assure you that your child is safe and if they need to remain at school we will continue to follow instructions from the local police and update you with further information when this comes to hand."

Matamata Intermediate said parents could collect their children from the Smith St entrance. Parents were asked not to go on to the school grounds but to ask staff in hi-vis vests to escort their children to them.