Law enforcement agencies are investigating a suspected arson at Harvard's Wolcott Gibbs chemistry laboratory following a Saturday night fire.

The fire, which fire officials say started on a desk in the basement of the Gibbs lab building, was quickly contained by the Cambridge Fire Department (CFD) before it could do extensive damage to the building.

At about 10:30 p.m. on Saturday, security guard Kandeh Bangura was on patrol around the Divinity Avenue labs when he smelled smoke.

He traced the smoke back to the Gibbs chemistry lab, where white smoke was plainly visible.

A quick search of the building turned up only one occupant, a female on the fourth floor, who was safely evacuated.

Harvard University Police (HUPD) officers arrived on the scene, and called CFD.

By the time CFD arrived, smoke hung thick in the air around Divinity Avenue and it had filled the chemistry lab.

CFD units, including the hazardous materials (HAZMAT) unit from around Cambridge responded to the fire, as officials feared it might spread to chemicals stored in neighboring rooms in the lab.

The fire, however, proved easy to contain and extinguish. CFD reported that the fire damaged a set of architectural drawings on a desk. Most of the damage was either smoke- or water-related.

"It was a room fire, just one room. We knocked it down pretty quickly," CFD Deputy Chief Edward Mahoney said.

The last CFD engine left the scene at around 11:30 p.m., about an hour after the fire was reported.

Windows in the building were still open Sunday afternoon as engineers tried to vent the smoky air from the building.

An officer of the Cambridge Fire Investigation Unit found signs that the fire may have been intentionally set Saturday night, and called in the Massachusetts State Police.

Officers from the state fire marshal's officer were on the scene by early Sunday morning.

An HUPD detective was on the scene by midnight Saturday night. He refused to comment on the case yesterday afternoon.

Mahoney would only characterize the fire as "suspicious," and declined further comment.

"The fire is still deemed suspicious, and is still under investigation," HUPD Sergeant James L. McCarthy said.

The Gibbs Lab was accessible through an adjoining construction site, and HUPD said that it was possible that someone might have gained entrance that way.

"This is really the beginning of the investigation, but we don't believe that it was any outside groups," McCarthy said.

"[The fire is] under investigation, and we'll have to wait to see what the state fire marshal says," John R. Lenger of the Harvard News Office said.