Firefighters battled an early morning fire Monday that destroyed a classroom and offices in the Lab School, one of the oldest buildings at California State University, Fresno.

The fire started about 2:45 a.m. between vending machines in a breezeway outside the Lab School on Keats and Jackson avenues, fire officials said.

Flames moved up a wall and into the attic before firefighters could contain it.

About 60 firefighters fought the fire for about two hours. Crews on the roof used chain saws to cut a trench through 6 inches of wood and roofing material to create a vent for the smoke and flames.

Classes inside the Lab School are canceled today. Most will reconvene Wednesday, but Room 128, the most severely damaged site, will not be used this semester.

Fresno State officials are looking for temporary locations for those classes to resume Wednesday.

The cause of the fire is under investigation. Fresno fire officials suspect arson.

Fresno Deputy Fire Marshal Clint Nichols said dispatchers received a call from a passer-by reporting a vending machine fire on Shaw Avenue, but the caller did not say the fire was on the university campus.

Fire engines arrived at the scene about six minutes after the call, he said. Once on campus, firefighters were led by smoke to the Lab School.

Investigators are following up on the initial fire call, Nichols said. "We wonder how they knew it was a vending machine." A narrow passageway makes it difficult to see the machines from the street, he said.

Dave Moll, director of public safety at Fresno State, said samples from a vending machine have been sent to a forensic laboratory. "All we know is the fire started in or around the Pepsi machine that was not plugged in. So, obviously the electrical fire theory can be ruled out. But then what are we left with? We haven't really determined what happened."

Fresno State Police Chief Michael Dunlap said a university custodian who works in the area of the Lab School and two newspaper delivery persons saw flames and smoke. They reported the fire to authorities. The university identified the custodian as Pa Kou Vang. Names of the newspaper carriers were not available.

This is the second fire this year affecting Fresno State students. On May 20, a suspicious fire destroyed 105 units at University Village, a three-story student apartment complex under construction near the campus.

On Monday, flames were shooting 15 feet above the roof of the Lab School when Moll arrived about 3 a.m. "It was really coming out of the roof. It was pretty amazing."

The fire destroyed a room that holds 10 classes, and extensive smoke and water damage left three offices unusable. Preliminary loss estimates are about $1.5 million to the structure. Value of the contents of the rooms -- computers, desks, chairs -- has yet to be calculated.

The Lab School houses Communicative Disorders and Deaf Studies, The Learning Resource and Tutorial Centers, Student Affairs, Student Support Services, the McNair Program, a post-baccalaureate program, and classes from various departments on campus.

The fire was concentrated in the northeast wing of the four-wing complex, Moll said. The learning center offices had some of the heaviest fire damage.

The center's director, Sonya Hildreth, and Puneet Sharma, a system and software consultant in the Division of Student Affairs, walked over broken glass and beneath sagging ceilings to salvage items from offices. "We're trying to retrieve laptops and other things," Hildreth said.

Sharma placed a miniature wooden ship and a smiling Buddha statue next to computer equipment on the walkway outside Room 134. He couldn't explain why he'd grabbed the small items from his desk.

Students watched in dismay Monday as firefighters mopped up behind yellow police tape.

Colleen Hunter, 21, drove from Yosemite Lakes Park near Oakhurst to the university at Shaw and Cedar avenues only to find her beginning acting class canceled.

"I had no idea this happened until I got here," Hunter said. "Unfortunately, my last class is also in this room. I don't know if I have any classes at all."

Lab School classes will be canceled today, but university officials said they will resume Wednesday in Rooms 101, 108, 163, 171, 177 and 181.

The fire caused University High School to close Monday when rooms lost electrical power. Those classes resume today.

The Speech and Hearing Clinic, operated by the Department of Communicative Disorders and Deaf Studies, will take appointments beginning Monday. Patients will receive individual calls about changes in the clinic's schedule.

Finding new office space can't happen soon enough for some Fresno State staff.

Nalla Lorton, a remedial math adjunct professor, tried in vain to enter her office in the Lab School, only to be stopped by security officers.

"I have a whole lot of computer work I was planning to do," she said.

Lorton also worried about students showing up for math and English tutoring sessions at the Resource Centers.

"They're going to have to open it somewhere, because the students need it."