Police were called to Cameron Road at about 8.50am on Tuesday.
Tauranga Girls' College told RNZ there was an "incident" out the front of the school and Police were then called.
The school was advised by Police to go into lockdown, it said.
The acting principal said everyone at the school was safe and nobody from it was involved.
The school sent an email notification to parents at about 9.35am asking them to not come to the school or try to contact their children.
"The school is currently in lockdown awaiting clearance from Police," it told parents.
"Please be reassured everyone is safe."
Police said the lockdown was later lifted.
"The person alleged to have a weapon was located, where Police found a knife in their possession, and taken into custody," they said.
"Police continue to make enquiries into the incident."
Gate Pā School said it was also put in lockdown after a man with a weapon was seen outside Tauranga Girls' College.
"We remained in close contact with Police throughout the situation. Once the offender was apprehended, the lockdown was lifted," it said.
"All students, staff and visitors followed instructions calmly and did an excellent job during the lockdown," Gate Pā principal Rochelle Jensen said on Facebook.
