A dormitory on the University at Buffalo North Campus in Amherst was evacuated Sunday night as an equipment malfunction near the boiler room caused carbon monoxide to build up in the building.

Two students drove to a hospital, and two others were taken to a hospital by ambulance, according to Joe Brennan, a UB spokesman.

An additional two students – the fifth and sixth in the incident – were evaluated by an ambulance crew and were not taken to a hospital.

The conditions of the students taken to a hospital were not immediately available, but they were not thought to be serious.

Brennan said the incident began to unfold at about 8:30, when students started to feel ill. The dormitory, Richmond Quad, houses as many as 500 students, although it was unclear how many were evacuated. Students who live in the dormitory went to other buildings on campus as they awaited an all-clear signal to re-enter, which was given at 11:15. None of the students had to wait outside in the bone-chilling cold.

National Fuel Gas sent a representative to the scene, and firefighters carried fans into the building to help ventilate it at 10:30.

The state fire marshal had a car at the scene. Also standing by was Twin City Ambulance and a ladder truck from the Getzville Volunteer Fire Company.