Chemical irritant sends four people to the hospital at high school in Brookline, Mass.

Two staff members and two students at Brookline High School in Brookline, Mass., were hospitalized after a chemical irritant was released inside the school. 

Students and staff were evacuated at 11:47 a.m. Thursday when the incident occurred near a first-floor bathroom, reports CBS News. 

Firefighters were ventilating the affected area and monitoring the air quality in the school Thursday afternoon.

Medical personnel were at the school to treat people who had minor symptoms.

Police said shortly before 2 p.m. that hazmat units had cleared the scene.

Officials are unclear of how the chemical got into the building.