A fire of suspicious origin gutted the historic Irving Junior High School early Saturday.

Nearby residents were evacuated because of fears that the fire in the vacant building could spread or a natural gas explosion occur.The 4:10 a.m. blaze began in the school's southeast gymnasium. It destroyed the east and central wings of the school, with some walls collapsing and several explosions occurring during the fire, fire officials said.

An investigation is in progress, said Gordon W. Nicholl, Salt Lake fire battalion chief.

It took 75 firefighters - from three different fire agencies - about 3 1/2 hours to control the blaze at the school at 2100 South and 1200 East. Preliminary damage estimate was $500,000.

"There's no question in our minds that this is suspicious in origin," Nicholl said. "I think the west wing of the building was saved as a direct result of the firefighters. I went to school there and I felt pretty bad watching that building burn down. It really saddened me."

Nicholl said when firefighters arrived the building was fully engulfed. Eleven engines, four ladder trucks and a hazardous materials response team were summoned to the area, Nicholl said.

The fire sent heavy smoke clouds into the air and awakened several nearby residents who said they notified police after hearing "loud explosions."

William Hall, who manages an apartment building across the street, 1985 S. 1200 East, said at one point the fire sent flames 30 to 40 feet into the air.

Hall also said he believes the building was purposely set on fire. "I'm convinced this was arson," Hall said. "It was like nobody cared. It seemed like it made no difference what happened to it (the school)."

Abby Mitchell, who also lives across the street from the school and who first called police about the fire, said she had been "waiting for this to happen.

"The building has just been sitting here for so long. It seems to me this was planned. It's a shame because it was such a beautiful building."

American Red Cross volunteer Robert Cutler, who taught industrial arts at the school in 1959, expressed sadness over the disaster.

"It was an artistic old building, but it really had physical problems 30 years ago," Cutler said. "It's sad to see it end up like this. I can't help but remember walking the halls and working with the kids."

Bob Dean, who also attended the school as a teenager, said, "I feel real bad. It was a beautiful old school, but it's been vandalized and gone to waste."

Bonnie White, who also lives in the area, said, "This is really a tragedy. It's another landmark that is now destroyed. It's just terrible it's come to this end."

The school, known also as Irving Commons, began as a Salt Lake school in 1919 and became a commercial arts and entertainment complex several years ago.

The 100,000-square-foot complex included three theaters, four arts-rehearsal studies, offices and other rooms that supported local artists and arts organizations. Jeff Long, Salt Lake fire investigator, said the building had been vacant for two years.

The adobe school building was an outstanding example of the Edwardian revival style of architecture, historians said. The school was built by Abraham O. Smoot and Ira Eldredge, two persons who played prominent roles in the early history of Sugar House.

The fire was under control at about 7:30 a.m., Nicholl said. However, firefighters remained in the area for four more hours to assess damages and water down the premises.

Firefighters evacuated residents living between Douglas Street (1250 East) and 2100 South. At one point, firefighters were afraid the fire could spread and that a gas main, which fed natural gas into the building, would cause an explosion.

The former school, sold by the Salt Lake City Board of Education in 1977, was remodeled in the early 1980s at a cost of more than $3.5 million.

Nearly all of its floors were hardwood, and the ceilings were more than 12 feet high. The renovation preserved the original architectural details.