A water line break Wednesday morning at Susitna Elementary in Muldoon led officials to close the school, but it should be open Thursday.
Most of the building was unusable Wednesday, according to the Anchorage School District.
Some children, including bus riders, arrived at school before the closure was announced. They were cared for in the gymnasium until parents picked them up.
A PVC pipe broke, according to the Anchorage School District's maintenance and operations director.
"Over time and years, materials weaken and sometimes, like today, break," district spokeswoman Catherine Esary said in an emailed response to questions.
Seven classrooms were flooded. Some books may have been damaged but no electronic equipment, she said.
"Maintenance and operation crews are working to correct the problem and clean the building," the district said in a statement.
The school will be open and ready for students Thursday, the district said.