Smoke and the smell of a burning odor forced hundreds of University of Wisconsin students to evacuate a campus building Tuesday.

According to UW Police Department officer Brent Grouber, the source of the minor fire at Van Vleck Hall was an air-handling unit in the utility room of the building's basement.

"It wasn't anything of concern like arson or anything of that nature," Grouber said. "It was a simple mechanical issue where a belt burned up a room in the basement, which caused smoke to go through the auditorium."

Lori Wirth, public information officer for the Madison Fire Department, also said the fire "wasn't major."

The rooms affected included B130 and B128 in Van Vleck, and Grouber said class was not being held in either room at the time of the evacuation.

Grouber added no student or faculty member was in any danger because of the fire.

"There was no danger to the community as long as people remember to evacuate the building right away when there is an alarm or visual strobe light," Grouber said.

Aside from a "burnt rubber smell," Grouber said there were no other noticeable problems with the building after the fire was extinguished.

Additionally, Grouber said the scope of the fire was limited.

"The smoke itself was contained because the doors were closed," Grouber said. "The smoky haze didn't even go into the lobby."

UW freshman Rob Smatlak was sitting in B130 Van Vleck waiting for his calculus class to start when he said the fire alarm went off, at around 12:45 p.m.

"All of a sudden, the room started filling with smoke out of the vents," Smatlak said. "It looked like it was a smoke machine — it was real, real white. The entire room was getting full of smoke."

Sophomore Andrew Bork was also in the classroom and decided to leave when smoke started to fill the room.

"I came in and saw there was a thin layer or smoke that was all across the top of the room. It got thicker and thicker very quickly," Bork said. "By that time, we knew we should leave the building. As we left, the fire alarm went off."

Both Bork and Smatlak said they could smell smoke when they immediately entered the class, and the stench got progressively stronger until the alarms went off.

Despite the minimal impact of Tuesday's fire, Wirth said it is important for students in general to evacuate a building when alarms ring so firefighters can do their job quickly.

"We just want to make sure students hear the alarm and stay out until firefighters say it's alright," Wirth said. "In a building that big, we want to make sure everybody is out of there until we can verify exactly what's going on."

Van Vleck — home to the UW mathematics department — is located on top of Bascom Hill, just south of Bascom and Ingraham Halls. Class continued as normal following the incident.

— Nick Penzenstadler contributed to this report.