Two students working with the chemical pyridine in a seventh-floor lab were hospitalized for observation

A building at the University of Minnesota reopened Thursday after being evacuated the night before when a chemical spill sent two students to the hospital for observation.

University officials reopened the Phillips Wangensteen Building once a hazardous material response team had cleaned up the spill.

Two students working with the chemical pyridine in a seventh-floor lab reported the spill about 6 p.m. Wednesday, Minneapolis Fire Battalion Chief Mike Carswell said. The students apparently were moving the toxic, highly flammable, chemical when 2 to 4 liters spilled in the doorway, spreading into the lab and the hall.

If the liquid had spilled only in the lab, the fumes would have been vented outside, said Neil Carlson, university health and safety industrial hygienist. But because the spill entered the hall, emergency crews were concerned it could be carried to the rest of the building, prompting them to immediately evacuate the building's sixth, seventh and eighth floors. The rest of the building, which contains classrooms and labs, was evacuated as hazardous material crews came to clean up the spill.

The students, who suffered no apparent injuries, immediately covered the spill with dry material to contain it and the vapors, Carswell said. As a precaution, the students were taken to a decontamination van, where they showered. They were later hospitalized for observation. There was no word on their condition Thursday morning, a university spokesman said.

Pyridine can irritate skin and the vapors can cause nausea and headaches, Carlson said.