About 150 officers from three area police departments swooped down yesterday on the popular heroin and cocaine market on Quarles Street NE by motorcycle, scooter, horseback, car and helicopter.

But the drug dealers knew of the planned raid -- one of the largest in recent memory -- and police officers found themselves outnumbering drug suspects. Out of 100 people rounded up, police were unable to say yesterday afternoon exactly how many arrests had been made in the operation. Earlier in the day a high-ranking police official said 35 people had been arrested before the raid because plainclothes detectives had seen them allegedly buying drugs.

The invasion began about 4:30 p.m. as an estimated 150 Washington, U.S. Park and Prince George's County police swept into the mainly public housing neighborhood and headed straight for 45th and Quarles streets, only to find the number of suspected drug sellers down by 50 percent.

The raid, called Operation COMPAC (Combined Operation of Metropolitan, Park and County), began in the morning with a few plainclothes officers hiding in vacant apartments, radioing descriptions of suspected drug buyers to officers waiting about four blocks away. About 35 people were arrested on drug possession charges as they left the neighborhood, said Deputy Police Chief Fred Thomas, head of the joint operation.

Other plainclothes detectives cruised through the public housing projects in unmarked cars.

But they fooled few in the neighborhood. "You can always tell which ones are the police," said a young man, who was trying to interest passers-by in purchasing a brand of heroin called "Cujo," about two hours before the raid.

Thomas said that he was not concerned if everyone knew of the raid.

"The junkies and the dealers have found [Quarles] to be an ideal location, with the federal park and the Prince George's County line right next door," he said. "We could take out an ad in the paper and they would still be there. What we are hoping for is a big display, a big show."

In March, D.C. officers cut down an acre of trees behind the housing project to wipe out a hiding place for dealers running from the law.

Yesterday's raid was an impressive show when the officers, dressed in uniforms of three different departments, stormed the block. Thomas, using a bullhorn and followed by a shotgun-toting officer, walked up and down, announcing that the area was sealed off and anyone leaving the block would have to pass through a check point.

Kimi Gray, who heads the tenant-run management company that now manages the Kenilworth-Parkside public housing project, said she welcomed the police operation even if the usual number of drug dealers and buyers was diminished.

"It is very important for the community to know that we will not tolerate anymore of this foolishness, this drug business," she said. "We have cooperated with the police. Our tenants are now willing to call the police on their neighbors. We are closing up the shooting galleries where users are injected with drugs . We don't want a Band-Aid. We want to get rid of the drug traffic."

But Michael Pollard, 25, a Kenilworth resident, said he thinks both Gray and the police are too optimistic about the raid.

"The older people who live here don't like the drugs," Pollard said. "But the younger ones are involved. They run the oil joints and they can make $600 a day charging $5 to get in and a $1 for the syringe. That is a lot of money and when one oil joint closes, another one will open."