Crack, a highly potent derivative of cocaine, is flooding illegal drug markets in the District and has overtaken PCP as the drug of choice, D.C. police officials said yesterday.

Crack and other illegal drugs are contributing to the escalating number of homicides in the District, D.C. homicide Capt. Larry D. Soulsby said at a news conference where he announced the city's 33rd homicide in January. That slaying set a record here for one month.

"Virtually every homicide is drug-related," said Soulsby. "There is no reason for the average citizen to be overly concerned, because almost every homicide is a buyer, seller or someone involved in the drug business."

Multiple weapons and more violence than before are associated with the homicides, Soulsby said. Often, an individual victim will be stabbed and shot or strangled, he said.

The increased violence has strained the police department, and seven additional detectives will be assigned to the homicide squad tomorrow, boosting the number of homicide detectives to 42, Soulsby said. He added that police were planning other antidrug programs, including a "new youth initiative," but he would not release details.

Soulsby and other police officials emphasized that the public needs to help the police stem the killings. Witnesses are often afraid to come forward because they fear retaliation or are involved in drugs themselves, he said.

The highly lucrative trade is enticing more juveniles than ever, police said. The number of slayings of juveniles rose from six in 1986 to 19 last year, police said.

Youths are used by drug dealers "who lure them with flashy cars, fine clothes and the promise of big money," said Soulsby.

The highly addictive and inexpensive crack sweeping into city neighborhoods is a form of cocaine that has been cooked and refined into a rocklike substance. It is chipped into small segments that weigh about 5 to 10 milligrams and usually are placed in small plastic bags, according to a narcotics detective.

The bags sell for an average of $25, the detective said, although bags can go for as high as $100. Crack is becoming more popular because the drug is cheaper than PCP and the high is considered better by the smoker, he said.

"You can get a quicker high," the narcotics detective said. " . . . It causes your heart to beat rapidly . . . . PCP is very undependable. You could have violent and bizarre behavior."

Drug-related murders may occur as a result of a fight between a buyer and a seller of drugs, a territorial dispute between drug dealers, a person who is under the influence of drugs or a person supporting a drug habit, police said.

Growing numbers of small gangs are involved in the drug wars, Soulsby said, and they often use semiautomatic or automatic weapons. Sixteen of the homicide victims last year were Jamaican, as were seven of this month's victims, police said.

The city's 33rd homicide, which topped the record number of 32 slayings in December 1971, was not drug-related. Kermit Hutchin, 51, of 16 Rhode Island Ave. NE, died Thursday.

Hutchin was admitted to D.C. General Hospital Jan. 5 after complaining of severe headaches and the limited ability to move his left arm and leg. An autopsy yesterday determined that Hutchin had been hit over the head with a pipe.

The 32 homicides in December 1971 were mostly domestic or "friend on friend" rather than drug-related, Soulsby said. Although heroin was popular then, "people didn't know of PCP or crack," he said.

Fifty-seven percent of last year's 228 homicides were drug-related, and 27 of this year's 33 homicides involve drugs, police said.

"As long as there is a demand in the community for drugs, there is going to be a problem," Soulsby said.