The bodies of five persons, each shot in the back of the head in what were believed to be drug-related killings, were found last night in a locked apartment in a large development near the Landover Mall shopping center, Prince George's County police sources reported.

The sources said that the dead -- four men and a woman whose identities were not immediately known -- were found lying face down throughout the apartment on the top floor in the three-story Village in the Woods development on Brightseat Road.

A sixth person, a woman who had been wounded in the neck, was found outside the apartment building at 2320 Brightseat Rd.

Police said they went to the scene, near an area that has been described as a notorious drug market, after neighbors reported hearing the woman's screams around 8 p.m.

While she was being taken to Prince George's Hospital Center, they said, the woman managed to say there were other victims in the apartment.

At first, police, suspecting that an assailant or assailants might be inside, remained outside the apartment. Heavily armed members of the police emergency response team were summoned, and about 10 p.m. police finally entered the apartment, using a passkey.

No suspects had been identified or apprehended by early today.

Police did not elaborate on their reasons for believing the shooting to be drug-related. However, a spokeswoman said last night that there had been reports of drug activity at the complex in the last two months. Neighbors also said they believed there was a thriving drug trade in the immediate area.

In addition, the complex lies just south of the Glenarden Apartments development, which police have come to call "crack alley" in recognition of its flourishing drug trade.

The shootings came one day after County Executive Parris Glendening announced an "action plan to fight the war against drugs," asserting that he would not tolerate drug activities in Prince George's. {Related story on Page D5.}

The plan was prompted by an upsurge in reports of crime, including many shootings and murders, linked to drug sale and use.

The five killings raise the number of homicides in the county this year to 12. Last year there were a record 96 homicides in Prince George's compared to the previous high of 86 in 1982.

A police spokesman said about 40 percent of last year's killings were believed to be linked to drugs.

Preliminary reports indicated that police believed that two men may have been responsible for last night's shootings.

A police source said it appeared that all the dead had been shot in the back of the head with a large-caliber handgun. He said the bodies were scattered throughout the apartment, in a bedroom, living room and kitchen. One of the dead was said to have used a wheelchair.

The woman who was wounded was listed in fair condition last night at the Prince George's Hospital Center, where she underwent surgery.

A nursing supervisor said that she had been shot in the hand as well as in the head or neck.

Her name and age were not disclosed.

In a brief interview last night, at least two neighbors said that there was drug activity in the immediate vicinity of the building where the shootings occurred.

Another resident of the complex who lives a short distance from the site of the shooting said the complex would be all right "if they could get rid of the drug addicts and drug pushers," whom he said he could frequently see from his apartment window.

When police would try to interrupt their activity, he said, they would shift operations a short distance away, and return when the officers left.

A neighbor said she believed that the apartment where the bodies were found had been occupied for the last few months by two women who appeared to be in their twenties. The neighbor said strangers The complex would be all right "if they could get rid of the drug addicts and drug pushers."

-- resident of apartment complex

appeared to visit the apartment at all hours.

The Village in the Woods development is just west of the Landover Mall shopping center, which lies at Landover Road and the Capital Beltway.

Late last night, blinds were drawn in the third floor apartment where the shootings occurred.

Through the blinds, onlookers outside the building could see the brilliant flashes of lights used by police investigators who were photographing the interior of the apartment.

Early this morning police were still searching the immediate surroundings of the building for evidence.

About 10 officers using bright lights were methodically examining the ground outside the building. Staff Writer Jeffrey Yorke contributed to this report.