Auckland's Botany Downs Secondary School has been evacuated after receiving a threat it considered credible.
However, after police inquiries it was decided the threat was a hoax and students were returning to class about 10am on Thursday.
Principal Karen Brinsden said all students, staff and other people on site had been safely accounted for and the evacuation process had worked smoothly.
"As a precaution, we have put in place actions moving forward and the police will increase external patrols around the school and local area over the next few days," she said.
The incident comes a day after another large Auckland college was evacuated due to a "threat to the school".
Western Springs College students were released at 1.30pm on Wednesday, the school said on its website.
However, police investigated and told staff the grounds were safe.
A Western Springs teacher said he had been told it was a bomb threat.
The school remained closed for the rest of the day.