A three-alarm fire that burned fiercely for 1 1/2 hours in the Navy's financial and accounting center in Crystal City Wednesday night caused $750,000 in damage, fire and Navy officials said yesterday.

The blaze, which started at 6:29 p.m. in Room 401 at 1931 Jefferson Davis Hwy., primarily damaged office furniture, some computers and other office equipment, according to Lt. Susan Glutting, public affairs officer for the Naval District of Washington.

She said there was no significant loss of financial records, since those documents are stored at the Navy Finance Center in Cleveland.

Officials said the cause of the fire is still under investigation, but added that they had definitely ruled out arson. Arlington Fire Department spokesman Lt. William Moultrie said officials sent some burned computer equipment to the Consumer Product Safety Commission laboratory to determine whether it may have malfunctioned and caused the blaze.

About 60 of the building's 2,100 employes, mostly military and senior civilian personnel in offices on the fifth through 11th floors, were able to work in the building yesterday as fire marshals and Navy officials raked through the charred debris and assessed the damage.

Offices on the second, third and fourth floors were closed yesterday.

With the exception of about 10,000 square feet on the fourth floor where the fire was concentrated, the rest of the building will be open today, according to Dale Bruce, director of public affairs for the National Capital Region of the General Services Administration.

The building, Crystal Mall No. 3, is owned by the Charles E. Smith Co. and occupied primarily by the Naval Accounting and Financial Center, the Navy Regional Data Automation Center, Naval Supply Systems and other military offices.

Moultrie said the fourth floor did not have a sprinkler system; the 17-year-old building was constructed before new fire codes mandated sprinkler systems in all high-rises, he said.

"Had this building had a sprinkler system, I think there would have been considerably less damage and considerably less hazard to firefighters," he said.

Fire Battalion Chief Claude Jenkins took the unusual step Wednesday of stationing firefighters by the exit doors on each floor so they could shout directions to other firefighters who could not see their way through the dense smoke.