A three-alarm fire caused more than $1 million damage last night to a Silver Spring high-rise building that is the headquarters for the National Weather Service, General Services Administration fire investigators reported.

Daniel Bathurst of the GSA said the 13th floor of the Gramax Building at 8060 13th St. was gutted by the blaze and that the 14th (top) floor of the building was also damaged by the fire.

In addition, there is water and smoke damage throughout the building, he said.

Dr. Richard E. Hallgren, head of the Weather Service, said early today that forecasting and data transmission operations are housed in another location and will not be affected by the fire.

However, Hallgren said, the entire building, where about 800 administrative personnel work for the Weather Service and its parent, the National Oceanic and Atmopsheric Administration, will be closed at least for today.

He said only senior supervisory employes at the division level should report for work.

The 13th floor housed the overseas operations, communications division and the aviator-weather division of the weather service, while he and other top administrators have offices on the 14th floor, Hallgren said.

Cleaning crews working on the building's 13th floor reported the fire shortly after 8:30 p.m., and it later spread to the 14th floor. The second alarm was sounded at 8:45 and a third at 8:51 p.m.

More than 100 firefighters from 15 Montgomery and Prince George's county units responded to the blaze, which took more than an hour to control and another hour to put out.

Officials said firefighters experienced difficulty because their ladders could not reach the floors on which the fire was burning.

Firefighters had to enter the building on the ground floor, travel by elevator to the 10th floor and then climb smoke-filled stairways to battle the blaze, officials said.

Officials said a half-dozen firefighters were treated on the scene for smoke inhalation, but that none was seriously injured.

There was no word early today on what caused the fire, and investigators said it would probably be early afternoon before any determination could be made.

Weather Service offices are on all floors of the building, except for the ninth, 10th and 11th floors, which contain NOAA offices, Hallgren said.

Although more than 50 workers from cleaning crews were in the building when the blaze was discovered, they all escaped without injury after a guard on duty in the building, identified as E.L. Sweeney, called in the alarm and ordered the workers to evacuate, fire officials said.

One man had been reported trapped in the building, but officials said later it was actually a firefighter signaling to others on the ground.

Hallgren said that word-processing equipment and some small computers on the 13th floor were destroyed in the blaze, but that no major equipment was damaged.