Students at Massey High School in west Auckland are being told to stay home after a fire in a block overnight.
The school said power was off and fire crews were still dampening down hotspots.
Senior students are on exam leave but Year 9 and 10 students were being told to stay home.
School trips would still go ahead.
The fire broke out at 11pm on Monday, with nine fire trucks, two ladder trucks and nine support vehicles sent to the three-storey building on Don Buck Road.