A wave of grief swept over the rural St. Mary's County community of Mechanicsville after Nicole McGinnis, 16, and her brother, David, 14, were killed in a car accident March 14. Dozens of teenagers staged a candlelight vigil at the site of the wreck, and friends read aloud heartbreaking poems at the siblings' wake.

"You knew this had affected their lives forever," Loretta McGrath, an aunt of the dead teenagers, said of the mourners.

Just 25 miles away, in Calvert County, a similarly tragic scene played out a short time later. After Sheena Creek, 17, was killed in a car crash March 15, hundreds of teenagers packed a small country church for her funeral. Her friends arranged a memorial of balloons and flowers at the crash site.

"It seems like the world is about to end," said Steven Plater, 18, at the memorial. "People are dying left and right."

It is a familiar refrain in Southern Maryland -- in the growing counties of Charles, Calvert and St. Mary's -- where traffic accidents have been killing young people at an alarming rate.

In the past 14 months, 11 people ages 14 to 19 have been killed in nine Southern Maryland traffic accidents involving teenage drivers. By contrast, in the same period, traffic accidents in the Washington area's two biggest counties, Montgomery and Fairfax, killed 13 teenagers. The combined population of Montgomery and Fairfax is about 1.8 million -- more than six times the overall population of Charles, Calvert and St. Mary's.

Teenage drivers were at fault in all nine of the fatal Southern Maryland accidents, police said. Authorities attributed seven of the crashes to inattention or speeding by teenagers. Alcohol was a factor in the other two crashes, investigators said. All but one of the 11 young people killed were wearing seat belts.

As for why so many deaths have occurred, "There is not any one answer," said Rebecca Martin, a traffic safety adviser for the Charles County Health Department. "It's a combination of everything."

Officials said growth in Southern Maryland -- where the population rose 24 percent in the 1990s, to 283,000 -- partly explains the high number of teenage deaths.

Southern Maryland's country roads, built for sparse, free-flowing traffic, often are filled with commuters, and side streets connecting new subdivisions to major thoroughfares are sometimes as busy as highway access ramps. As a result, officials said, the area's roads can be a deadly arena for young motorists with relatively little driving experience.

"These cemeteries are loaded with tombstones for teenagers," said Kathryn Orosz, 46, of Crofton, whose 18-year-old son, Michael Vito, died in a Calvert car crash in 1999.

Sheena Creek was a cautious driver, said her father, Elmer Creek Sr.: "We would come to a busy intersection, and I would tell her to 'Go!' when I saw a chance. But she would say, 'No, no,' and wait."

About 9:45 p.m. on March 15, she kissed her father goodbye and headed out to a Saturday night movie, saying she would return about midnight. She died minutes later, a few hundred feet from her home. The crash occurred as she was leaving her neighborhood, turning from a side street and onto busy Route 4. She was trying to make a left turn and pulled into the path of a sport-utility vehicle.

"I've been thinking, 'What was going through her mind?' " said her mother, Doris Creek. "I guess that is a question I won't ever have an answer for."

Along with at least three of the other fatal crashes involving teenagers in Southern Maryland, the accident that killed Creek fit a pattern. She and the others died while making left turns onto major thoroughfares from side streets.

In each case, making such a turn required crossing one side of the thoroughfare, stopping in a narrow median between the northbound and southbound lanes to watch for oncoming traffic, then proceeding again. "There's not much room for error," said Detective Chris Parsons of the Calvert sheriff's office, who investigated some of the crashes.

Kristin Runyon, 17, died July 17 in Huntingtown, not far from where Creek was killed. She was trying to turn left from Ponds Wood Road and onto Route 4. She apparently misjudged traffic and her vehicle was struck by a motorcycle, police said. Alexandra A. Denevan, 16, died Aug. 22 in the same area, also while trying to turn left onto Route 4. She was turning from Lower Marlboro Road when her vehicle was hit by a pickup truck, police said.

In St. Mary's, Nicole and David McGinnis were with a 16-year-old friend who was driving a station wagon in Mechanicsville. The driver, who was not identified by police, tried to cross Route 235, one of Southern Maryland's busiest roadways. The station wagon was struck broadside by a dump truck, killing the McGinnis siblings.

The similarities in the crashes prompted some officials and concerned residents to call for more stoplights along Southern Maryland highways. "They need to take more engineering steps to make the roads safe here," said Scott Pasch, president of the Drive Safe Driving School in Calvert and St. Mary's.

Calvert's Board of County Commissioners has asked the state to change the angle at which Ponds Wood Road intersects Route 4, to make it easier for drivers approaching the highway to see oncoming traffic. But Commission President David F. Hale (R-At Large) said such a project is unlikely given the state's deep budget deficit.

He also said that many residents moved to Southern Maryland to escape the stop-and-go traffic common in bigger counties. "For every person who wants a traffic light," Hale said, "I can find one who wants to take one out."

Another likely reason for the disproportionate number of teenagers killed in Southern Maryland crashes, officials said, is the fact that a large number of young people in the three counties are licensed drivers.

According to the state Motor Vehicle Administration, 11,874 Southern Maryland residents ages 16 to 19 are licensed to drive, accounting for 6 percent of licensed drivers in Charles, Calvert and St. Mary's. By comparison, teenagers comprise 4 percent of licensed drivers in Montgomery and 3 percent in Prince George's County.

And those Southern Maryland young people drive a lot.

The region's population is dispersed, and teenagers say most of their scant social options -- such as passing time on Saturday nights at a shopping mall -- require driving. Even a trip to a classmate's house can mean a 40-minute drive on dark, two-lane country roads with no shoulders or sidewalks.

"You get used to it," said Mike Clementi, 17, a senior at Great Mills High School in St. Mary's. "But you never know what to expect on the road."

Teenagers who do not have cars often catch rides with friends. Of the 11 teenagers killed in Southern Maryland in the past 14 months, seven died in cars with other young people, police said. Of those seven, four were passengers.

The Maryland Senate this year passed a bill sponsored by Sen. Roy P. Dyson (D-St. Mary's) that would have banned motorists younger than 18 from driving with passengers, except immediate family members, for six months after getting their driver's licenses. But the measure failed in a House committee.

Law enforcement officials, meanwhile, wonder how they can stop young, inexperienced drivers from making poor decisions on the road.

"It's difficult to say we're going to go out and prevent this from happening," said 1st Sgt. Michael Thompson of the Maryland State Police. "How do you attack it? It's just tragic."

Nicole McGinnis, 16, of Mechanicsville died March 14 in a car accident in St. Mary's County.David McGinnis, 14, was killed in the same crash on busy Route 235 that claimed the life of his sister.Kristin Runyon, a graduate of Calvert High School, was killed in a car accident July 17. She was 17.Two memorials mark the intersection on Route 4 in Calvert County where 17-year-old Sheena Creek was killed in a car crash. The busy intersection is only about a block from her house.