The fire appeared to start at a workstation in a chemistry lab around 2 a.m. Thursday, the Minneapolis Fire Department tweeted.
Sprinklers helped control the fire and prevent it from spreading to other areas, but there is water to clean up, WCCO notes.
All students and staff are safe, and no injuries were reported.
Thursday's closure affects all events, including Community Education classes, athletic events and extracurricular activities at the school, MPS noted.
All staff who work at the school should not report to the building, including those who normally do during weather closures.
Students and staff are encouraged to participate in coursework and discussions online, the statement said.
All other Minneapolis Public Schools are open Thursday.