The grieving friends arrived just after noon yesterday -- the girls red-eyed, clutching bouquets and each other, the guys tight-jawed and silent. They stood on the shoulder of busy Route 198 in Burtonsville and stared, trying to comprehend the skid marks and distorted metal where two teenagers had been killed 12 hours earlier.

It was the second deadly accident on Montgomery County roads since late Friday. It would not be the last.

An hour after the single-car crash in Burtonsville, on the other side of the county in Poolesville, another car hurtled off the asphalt, plowing 50 feet into a tangle of trees, vines and brush along West Willard Road and killing two teenagers. Montgomery County police said the 1991 Plymouth Laser was among more than a dozen vehicles gathered for drag racing on River Road. The crowd began scattering when officers arrived after being alerted by a neighbor. The car that crashed was fleeing north with no one in pursuit, police said.

All told, from 11:30 p.m. Friday to 1:15 a.m. yesterday, five teenagers lost their lives in the three accidents. Four were seriously or critically injured. The victims were 16 to 19 years old.

"We can't have another weekend like we had this weekend," Montgomery Police Chief J. Thomas Manger said in detailing the ages and circumstances involved.

Although each fatality had its own particulars, he said, all involved excessive speed and inexperienced drivers. "These five fatalities . . . are going to affect a lot more than these five families," Manger said. "There's going to be a ripple effect at the high schools [these] students went to, and in fact I believe there's going to be a ripple effect all through Montgomery County."

In the Burtonsville crash, police are awaiting the results of toxicology tests conducted because, they say, there was a strong odor of alcohol in the 2004 Plymouth GTO destroyed there. Its driver, Robert Middaugh of Laurel, was less than a week shy of his 18th birthday. He had been driving east when he lost control of the car just before the light at McKnew Road. The skid marks curved right, then left, then right, then vanished.

The car slammed into alight pole, grounded in a three-foot-wide concrete base, so hard that the base visibly shifted. The overhead intersection light whipsawed, with part of it shattering on the ground.

Middaugh, a senior at Atholton High School in Columbia, died at the scene, as did one of his two passengers, Michelle Timchalk, 17, of Laurel.

"They get in those cars and they think they are invincible," Jade Boesen said yesterday afternoon as she watched her daughter, Tara Butler, in a tearful, almost desperate embrace with two other girls. They sat within inches of the thick steel traffic pole that had ended the swerving trajectory of their friends' car just before 11:30 p.m. Saturday.

A neighbor heard the protracted screech of tires and then three bangs. "Like boom, and then boom boom," recounted David Lewis, who calls this stretch of Route 198 the "Burtonsville death trap." He ran out and saw the car smoking. The only survivor was in the back seat screaming.

Mary Kathleen Collins of Laurel was flown to Maryland Shock Trauma Center in Baltimore, where she spent hours yesterday in surgery. The 16-year-old athlete's legs were crushed in the collision, and surgeons were trying to save them, said a priest who had visited with her family.

"They're holding on to their faith. They're obviously devastated," said the Rev. Larry Young of St. Mary of the Mills Catholic Church. Last night, Young led a prayer vigil in Laurel for all three victims, part of the close-knit community involved in the area's parochial schools.

Each of the weekend's accidents occurred on a curve in the road. The first, Friday night at Norbeck and Norwood roads, ended with massive damage to the Volkswagen Jetta in which 16-year-old Alicia Betancourt was riding. She was pronounced dead at the scene. The 16-year-old driver, Hersh Kapoor, remained in critical condition at Maryland Shock Trauma Center last night.

The third fatal crash came in Poolesville on a remote strip of road made even more isolated by fields on one side and dense woods on the other. Again, the aftermath was the same: paint marks tracking the vehicle's final trajectory, wreckage of seats and visors and side panels, an acrid smell.

The two teenagers killed there were driver Edward Monterroza, 19, of Damascus and his front-seat passenger, Elmer Martinez, 18, of Wheaton. The two back-seat riders, both enrolled at Watkins Mill High School in Montgomery County, were Rico Scott, 17, of Gaithersburg and Alvin Monterroza, 16, of Montgomery Village.

The 16-year-old, who was thrown from the car on impact, was taken by helicopter to Washington County Hospital, where he was treated and released yesterday. Scott was flown to Prince George's Hospital Center with what police termed serious injuries. Accident reconstruction teams are still calculating how fast the car was going when it ran into the trees.

In his remarks last night, the Montgomery County police chief focused on the drag racing that officers are sure was the genesis of that crash. It follows a crash blamed on racing that killed a 16-year-old in Northern Virginia this month.

Manger pledged increase vigilance on such stretches as River Road, which he labeled "notorious for people drag racing."

"We have got to get the message out that these teens have to drive like they have something to lose," Manger said. "Because they do have something to lose."

Robert Middaugh and Michelle Timchalk, both of Laurel, died at this spot in Burtonsville.