The historic, red-brick Prince George's County courthouse, with its columned facade, 19th-century bell and trademark domed cupola, was gutted by fire yesterday, a few months before it was scheduled to reopen after a $25 million renovation.

Much of the two-story building -- which was largely vacant because of renovation work -- was reduced to a smoking ruin by wind-driven flames that ravaged the interior, claimed large sections of the roof and left only the charred skeleton of the cupola, which had overlooked Main Street in Upper Marlboro for 64 years.

The cupola's 124-year-old bell fell through the second floor during the fire and was buried in the rubble, officials said.

County investigators said late yesterday that they had not determined the cause of the fire or exactly where it originated, though it began on the right side of the building.

The 151,000-square-foot courthouse became a wing -- the Duvall Wing -- of the county's Criminal Court Complex in 1991, when a modern, 360,000-square-foot courthouse opened, attached to the old one by walkways.

Court records were long ago moved to the newer building, comprising the Marbury and Bourne wings, which sustained only minor damage yesterday, authorities said.

They said neither Circuit Court nor District Court, located in the new building, would be in session today.

The blaze was reported at 8:26 a.m. At its height, towering flames shot through the roof and licked out the structure's tall, elegant windows.

"The firefighters went inside and tried to get to the roof, where the fire had spread, but determined it was too dangerous and difficult to fight it that way," said Lt. Col. Marc Bashoor of the Prince George's fire department. "They absolutely made the right decision. Instead, they approached the fire from the rear and from the sides."

Bashoor said more than 55 construction workers were interviewed about the fire. He said investigators are looking at construction activity as a possible cause.

Because of winds from the north that Bashoor said were close to 30 mph, the blaze spread quickly through the wooden interior of the building and along the roof. The brick exterior, he said, was not in danger of collapse, even though intense heat can weaken a brick structure. "I walked inside the front of the building, and it was just pure devastation and catastrophic in terms of the damages," Bashoor said.

Acting Fire Chief Lawrence Sedgwick said it could be a few days before an official damage estimate is made, although County Executive Jack B. Johnson (D) said the figure could be close to $40 million.

Sedgwick said the fire quickly escalated to a four-alarm blaze that required about 165 firefighters to extinguish. He said three firefighters suffered minor injuries. One was taken to a hospital with a hamstring injury, and two were treated on the scene for heat exhaustion.

Calling it the "biggest fire in Prince George's history," Johnson said the old portion of the court complex "pretty much burned down." But he vowed to begin rebuilding as soon as possible. He said the county had a $100 million insurance policy on the building. "We lost our most historic building in Prince George's," he said.

Onlookers thronged the usually quiet streets of Upper Marlboro as the firefighters battled the blaze.

Tanya Oswald, 41, had a clear view from behind the register of the 7-Eleven store on nearby Water Street. "It started out with just the smoke, and then flames coming out, and then more black smoke," Oswald said.

Although there were no serious injuries reported and no apparent loss of records or files, residents and courthouse employees were heartbroken at the devastation.

"That was our home," said Jean Hahn, executive administrative assistant to Circuit Court Judge James Lombardi. She said the judge's office was to return to the courthouse in January. "We were getting ready to go home."

Mary Anderson Lane, the courtroom clerk for Circuit Court Judge E. Allen Shepherd, said she felt an enormous sense of sadness as she watched the fire.

Lane has worked at the courthouse her entire adult life. She said she began working there 30 years ago, in the marriage licensing division.

"A friend of mine's on fire," Lane said. "It seems like an old friend's burning down."

Lawyer Bill Hale, walking away from the smoldering structure, said: "We are losing history."

Officials said the renovation, which began in May 2003, was scheduled for official completion Jan. 13. There already were new carpets down, and much of the new ceiling had been installed. Many of the wood fixtures, such as doors and benches, still were out being refurbished.

When the building was shut about two years ago, eight judges who had their chambers there were displaced either to the county administration building or to offices in the newer wings of the courthouse.

The judges were to begin moving into their refurbished offices in January or February, officials said.

"I'm very disappointed," said Circuit Court Judge Sherrie L. Krauser, who was preparing to move back into her office in the old wing. "We're all sad. There's a lot of history in that building."

The courthouse dated to 1881 and recalled the time when Upper Marlboro was a rural tobacco town near the docks of the Patuxent River.

In 1939, the rambling Victorian structure was substantially rebuilt, with a neo-Georgian facade that included four cast stone Ionic columns and the look of an Ivy League college. By then, "Victorian gingerbread was not what everybody wanted," said county historian Susan Pearl. "They wanted the neo-classic Georgian university campus building, and that's what they got." Total cost: $178,000.

Its dedication on Oct. 29, 1940, was attended by many dignitaries, including Maryland's governor, Herbert R. O'Conor, and the president of the Upper Marlboro Board of Town Commissioners, T. Van Clagett, according to the event's program.

A band from a dairy played the national anthem as well as the county song, "Hail Prince George's."

There were additions in 1947 and 1969, but the courthouse retained its homespun, small-town flavor until the sprawling, $80 million Marbury and Bourne wings were added in 1991.

Fire department spokesman Mark Brady remembered rushing into the courthouse to get his marriage license 25 years ago -- that he was "dropped off at the corner, and we ran in."

"This place holds a lot of memories for a lot of people, good and bad," he said.

Staff writers Ruben Castaneda and Hamil R. Harris contributed to this report.

Bowie firefighters work on the flames near the courthouse's bell tower. The bell fell into the rubble two floors below.