Western Heights High School students have been allowed out after a two hour lockdown.
Just after 1pm the classrooms were evacuated, and students were sent to the school courts and turf after a potential bomb threat.
Emergency services were at the scene this afternoon.
The school has a roll of 1300 pupils in Year 9 and above.
Brian Rae came down to the school to check on his son, Bailey Rae in Year 10 who is epileptic.
"He has had no lunch if he doesn't eat or drink he could go into a seizure for it.
"We weren't notified, if there is a problem the school should notify the parents straight away."
Rae said the safety of his son was the ultimate priority.
"But then again, if his health deteriorates because of this, then who pays the price?"
A woman quickly called her son when she heard of the bomb threat and although he was fine, she said it was a scary situation.
"He is fine ... they are on the courts evacuated from the classes."
She said she also received a notification from the school that parents and caregivers were not able to go to the school and no one was being let on to the grounds.
A Year 11 student told the Rotorua Daily Post the students were being kept on the basketball courts.
"There is all 1300 of us located on the basketball courts and most of us have no idea what is going on.
"The police have cleared the classrooms to our belief and are now searching our bags one by one.
"The teachers have put us into straight lines, some of us are now a bit worried but still trying to keep calm," he said.
Megan O'Connor is one of the worried parents waiting outside the school gates.
She came to pick her daughter up for an appointment at 1.10pm.
"They wouldn't let me in, they told me it was a fire drill. The alarm was going off, and the gates were open. I saw one child leave, but then five cop cars arrived and the gates shut.
"We were told to move our cars to one side so emergency services could come through, and that it wouldn't be long.
"It's now past 2pm and I'm still here.
"I just want to reach my daughter, but I can't contact her. Nothing."
"I just want to know she's alright. Even that they're doing everything they can to calm a mother's nerves down."
A marked police car is now guarding the main entrance to the school, and cones have been put up to keep people away from the gates.
Another mother at the gates, who wanted to be known by her first name, Shona, has two children and two nephews at the school.
"My son has anxiety so I pick him up at lunch but when I got here at 1.20pm it was already closed.
"They won't tell us nothing. I don't know where my kids are. Just for them to say they are safe would be nice."
Police and Fire and Emergency New Zealand staff inside the school have moved away from their vehicles near the gates and towards the classrooms.
The school said on its Facebook page that students and staff had been evacuated and asked that parents stay away from the school.
"The school is currently in lockdown due to a bomb threat received by the police. All students and staff have been evacuated safely from the buildings.
"We are under the instructions of the police who request that parents do not come to the school as we cannot allow access at this time. We will post further updates. Thank you for your co-operation," the post said.
A police media spokeswoman said police had been made aware of a threat made in the Rotorua area and are in the area making inquiries. As a precaution, a school on Old Quarry Rd had been evacuated.