Students with midday classes in Mason Laboratory on Wednesday enjoyed listening to lecture outdoors but also had their ears filled with the drone of the alarm that went off in response to a small fire.

The fire broke out this afternoon in a furnace that had been left on in associate research scientist Sungchul Lee’s lab. The furnace burnt a hole, about 4 inches in diameter, in a wooden table, but no one was injured, and no experiment was taking place when the fire started, according to William Cross, a University fire inspector.

The fire occurred during a weekly meeting of chemical engineering graduate students. When one of the students entered Room 220, he smelled smoke and pulled the fire alarm, said Gary Haller, a professor in chemical engineering. The alarm went off at 12:12 p.m., and three fire trucks arrived on the scene within minutes.

A crowd of about 50 professors and students gathered outside the building waiting to be let back in, including Stuart Gottlieb’s international studies class, which dispersed when it became clear the alarm was not a drill. Meanwhile, one professor continued his lecture sans smartboard.

“The search for knowledge knows no bounds,” physics department chair Douglas Stone told his Physics 410 class.

The alarm was left sounding until 12:32 p.m., and people were allowed back into the building by 12:51 p.m.

Changchang Liu GRD ’14 said the last fire in Mason was over the summer, when a bottle of acid waste generated dangerous fumes, and the building was closed for a day.