D.C. Fire Chief Theodore Coleman yesterday called the four-alarm fire at U.S. Postal Service headquarters Monday night suspicious in origin, as officials of the Public Broadcasting System released a damage estimate that called their technical equipment housed in the building a total loss.

Although there was no specific reason to consider arson as the cause of the L'Enfant Plaza blaze, Coleman said, its origin was viewed as suspicious because of the speed with which it spread.

Mary Jane McKinven , a spokeswoman for PBS, said insurance investigators and PBS officials toured the building yesterday, and that much of the loss involved broadcasting transmission equipment, tape and editing machines and computers. The condition of about 100 program tapes recovered has not yet been determined, McKinven said.

She said a "preliminary estimate" of damage to PBS property was more than $12 million. Damage throughout the building has been estimated at $100 million by D.C. fire officials.

"When a fire was of such magnitude to cause real problems" by the time firefighters had arrived, Coleman explained, "that's when we classify it as suspicious." He said that the fire at Postal Service heaquarters, which investigators say may have caused as much as $100 million in damage, "spread faster than it should have." He added, however, that "We have no reason to specifically consider arson" as the cause.

Coleman said that investigators have not ruled out the possibility that the cause of the fire was accidental. Fire officials "can't say" if that is the case, he said, but "if through further investigation, the cause turns out to be something different than suspicious , the classification will be changed."

Coleman said that fire investigators still have to interview security guards, custodians and elevator operators in the building "to get a feel for what happened."

He said there were "large volumes of debris" from the ninth floor -- where the fire originated -- that have to undergo labratory tests before a final determination can be made on the cause of the blaze. He said he expected the results of those tests in about a week.

It is unknown what time the fire started, Coleman said, and "we cannot determine how long it was burning" before firefighters arrived.