Seven Teenagers - three boys and four girls - were killed last night when their pickup truck smashed into a tree and turned over on a rural road near Fort Meade in Anne Arundel County.

Five other persons were injured, three of them critically, in the crash, which occured about 9:30 p.m. on a dark, curving stretch of Patuxent Road near the Prince George's County line and about two miles south of the Army base.

A Maryland state police spokesman called the death toll the larges in an auto crash in the state in the past 10 years and possibly longer.

The identities of the seven boys and five girls riding in the pickup could not be learned immediately. Two of the boys were identified as dependents of military families at For Meade.

Three persons pinned in the smashed cab of the pickup were all dead on arrival at Anne Arundel County hospitals.

The nine persons riding in the rear of the vehicle, which was not enclosed, were spilled out onto the two-lane road, according to Chief Art Spencer of the Arundel Volunteer Fire Department.

They wer still lying there, about 15 feet from the pickup, most of them bloody and unconscious, when Spencer's rescue truck arrived shortly before 10 p.m., he said.

Of those riding in the back of the vehicle, four were reported dead on arrival at hospitals, Spencer said.

He said three paramedic units tended to the injured. Under emergency lighst, paramedics began administering intravenous fluids, taking electrocardiograms and splinting fractures.

Three of the injured, all listed in critical condition early today, were flown by state Police helcopter to the shock trauma center at University Hospital in Baltimore.

Two youths, both identified as military dependents, were taken by ambulance to the U.S. Army hospital at Fort Meade.

One of the youths, and 18-year old, was being treated at Fort Meade early today for multiple lacerations. The other 16-year-old, was transered to Walter Reed Army Hospital for treatment of a fractured vertebra.

One of the dead, a girl, was taken to Anne Arundel General Hospital in Annapolis. The others - three boys and three girls, were taken to North Arundel Hospital in Glen Brunie, authorities said.

According to authorities, the accident occurred while the vehicle was southbound on Patuxent Road near the Conway Road intersection.

The pickup left the right-hand side of the roadway at a point where rescue workers said the unlit road bends sharly.

The vehicle "struck a tree and rolled over," according to police.

Persons who visited the scene afterward described the tree as a "couple of feet" in diameter. They said the vehicles's cab was flattened and all its windows were smashed.

Two helicopters, one belonging to the Maryland state police, the other to the U.S. Park Police, landed at a shopping area some distance from the crash site.

The three victims flown to Baltimore were transferred from ambulances to the helicopters at the shopping area.

No cause for the accident could be learned immediately. It was not known where the youths had been nor where they were going.

The vehicle in which they were riding was described as relatively new, resembling a combination of a standard automobile and a pickup truck.