Emergency officials evacuated Portland High School this morning after a chemical reaction in a chemistry lab led to strong odors in other parts of the building.

Students in a class on the third floor were mixing substances which resulted in a chemical reaction at 9 a.m., fire officials said. The mixture overflowed the beaker beneath a ventilation hood and the fumes were drawn outside.

However, the school’s heating and ventilation system blew the fumes into a classroom on the second floor, officials said.

Nobody was injured in the incident, but officials evacuated the building and called the department of Environmental Protection as a precaution. Today’s damp, cool temperatures may have caused the fumes to settle more than normal, fire officials said.

One student was taken to the hospital, but that was for an illness unrelated to the chemical incident.

Students were sent home for the day.