A two-alarm fire roared through part of Saybrook College Saturday night, gutting the Master’s House on High Street but leaving the majority of the college undamaged.

New Haven firefighters responded to the scene at approximately 10 p.m., shortly after the fire was reported, and were able to prevent the fire from spreading to the rest of the Saybrook construction site, including student rooms. Three firefighters suffered minor injuries while fighting the fire.

“The fire doors did their job, and the building was fairly well encapsulated by the other buildings,” Yale Fire Marshal Michael Johns said. “The fire started to extend into the second floor and was stopped there.”

While the fire did not spread to the third and fourth floors above the Master’s House, several Yale administrators said the rooms on those floors were damaged by the smoke from the blaze.

Saybrook is scheduled to reopen to students this fall, after the finishing touches are put on extensive renovations that began more than a year ago. Several Yale officials predicted Monday that the fire would not prevent students from moving into Saybrook on time when school begins.

Johns said the fire was likely caused by the spontaneous ignition of flammable construction materials inside the house, which was being used as a staging area for renovation work throughout the college, although he said the investigation was ongoing.

“We suspect that it was probably caused by the ignition of rags left in a corner,” Johns said. “There is also the possibility of careless smoking.”

He said there was no reason to suspect arson, particularly because there was a security guard on site and a Yale police officer stationed nearby.

“The site was loaded with flammable liquids,” Johns said. “It’s hard to avoid stuff like that during construction.”

Witnesses said the fire produced so much smoke that Harkness Tower could not be seen from Elm Street.

Two New Haven firefighters were injured when they fell though a railing and down a floor inside the dark, smoky building. A third was overcome by heat exhaustion on the hot and humid night.

The 15-month long, $48 million overhaul to Saybrook was on schedule and more than 80 percent complete before the fire, according to a report sent to administrators last week.

Johns said a dollar estimate of the damage was not yet available. Director of Project Management Arch Currie said damage was easily in the hundreds of thousands of dollars.

While Saybrook students appear unlikely to be displaced by the fire, Saybrook Master Mary Miller and her family will most likely not be able to return to a newly refurbished residence as planned in late August.

“[The master’s house] was pretty much destroyed,” Currie said.

Miller is on vacation and could not be reached for comment Monday.