Hartford Public High School was evacuated and a student has been detained after two fires broke out in the building at 55 Forest St. Thursday morning.
The fires started in the boys' bathrooms on the second and third floor, according to fire officials.
Police said garbage and paper were burned in two bathrooms and there was video and other evidence leading authorities to a male student who is suspected of setting the fires.
The damage was contained to the two bathrooms, police said.
No one was injured, but students were dismissed for the day to allow the building to ventilate. School will be in session on Friday, according to Hartford Public Schools officials.