An ambulance is parked outside the emergency room of a hospital in Seoul. This photo is not directly related to the story. (Yonhap) Seventeen people were hospitalized Thursday after toxic bromine gas leaked from a university laboratory in Cheongju, North Chungcheong Province, prompting an emergency evacuation and a local disaster alert.The leak occurred at around 7:13 p.m. on the sixth floor of Chungbuk National University's Advanced Bio Research Center, after a 500-milliliter reagent bottle containing bromine was dropped and broken, according to police and fire authorities.Authorities believe the accident happened while students were handling chemicals in the laboratory. Bromine, a toxic substance that can vaporize at room temperature, quickly spread through the building after the bottle broke.The 17 people, including two students who were inside the laboratory, were taken to hospitals after complaining of symptoms including breathing difficulties, nausea, dizziness and eye irritation. None were reported to be in life-threatening condition.About 30 others inside the building were evacuated. Fire authorities said they deployed 15 vehicles and 24 personnel to contain the leak and clear the scene.Cheongju city sent an emergency disaster alert shortly after the accident, advising nearby residents to avoid the area and asking drivers to take detours.Police and fire authorities are investigating the exact circumstances of the accident, including how the reagent bottle was dropped and whether safety procedures were properly followed.