In this file photo, traffic flows along interchanges that link I-495 and I-270 in Bethesda (Katherine Frey/The Washington Post)

It was a deadly Labor Day weekend on the Washington region’s roads with at least seven people on motorcycles and the driver of a car killed in a string of unrelated crashes, according to law enforcement authorities.

In addition, a pedestrian was killed in the Oxon Hill, Md. area late Monday, the Prince George’s County police said.

The fatalities occurred between early Saturday and Monday night, with three motorcycle deaths reported in Virginia and four in Maryland.

In one of the incidents, a man was thrown from his motorcycle and then struck by an auto that did not remain at the scene, the Prince George’s police said.

The weekend marks the end of what is typically the deadliest three months of the year on the nation’s roads — the stretch between Memorial Day and Labor Day.

John Townsend, a spokesman for AAA Mid-Atlantic, said 40 percent of all traffic fatalities in the District, Maryland and Virginia occur in these three summer months. He also noted the pleasant weekend weather that made it “an ideal time for motorcyclists to ride.”

Townsend said Prince George’s County is one of the deadliest areas for motorcyclists in the region, along with Fairfax County and the District.

Prince George’s police reported three deaths in separate motorcycle crashes. The latest was Monday evening in the Forestville area, on Ritchie Road. Before that, a fatality occurred about 8 p.m. Sunday on Baltimore Avenue north of the University of Maryland campus in College Park.

In the Ritchie Road crash, county police said the motorcycle left the roadway in the 1600 block about 6:40 p.m. and its operator, 25-year-old Marc Yearwood Jr., of District Heights, died at a hospital.

An investigation showed Yearwood lost control of the motorcycle after landing a wheelie, and the bike hit a curb and struck a fire hydrant.

Sunday’s fatal incident in College Park began about 7:35 p.m. when an officer patrolling in a marked cruiser spotted a motorcycle heading south on Baltimore Avenue at high speed, police said.

As the officer approached, the motorcyclist made an illegal U-turn into oncoming traffic, drove onto a sidewalk, and then began going north on Baltimore, the police said.

The officer began heading north himself, and tried to make a traffic stop, but the motorcycle sped off, going into an intersection against the light, police said.

The officer was instructed by a supervisor “to disengage,” the police said.

Having turned off his lights and siren, police said, the officer went north along the motorcycle’s route. About a half mile away, at Fox Street, police said, the motorcyclist went into oncoming southbound traffic, and through the intersection, against the light. The motorcycle collided with a car that was trying to turn south onto Baltimore, the police said.

On Monday night, the police said Oscar Hernandez, 17, of Chillum, died on the way to a hospital.

In a fatality that occurred earlier on Sunday, a motorcycle crashed at Kenilworth Avenue about 3:45 a.m. at Kenilworth Avenue, near Route 295 and Eastern Avenue, authorities said.

On Monday night, Prince George’s police identified the operator of the motorcycle as Hjalmar Melendez, 47, of Germantown, Md. They said he struck a median, was thrown from his motorcycle and was struck by an auto as he lay in the roadway.

The auto did not remain at the scene, the police said.

In Calvert County, the sheriff’s office said a motorcycle operator was killed Saturday when in the Saint. Leonard area.

They said Kyle Eugene Joseph Mishou, 31, of Saint Leonard, turned right from Parran Road onto Route 4. Shortly afterward, they said, he lost control of the motorcycle and he was thrown from it. He died at the scene, the sheriff’s office said.

In an automobile incident, police in Montgomery County said a 69-year-old man was killed Saturday when the 1984 Mercedes-Benz he was driving went off the road and struck several trees in Wheaton.

The crash occurred about 4:45 p.m. in the southbound lanes of Hawkesbury Lane, approaching Randolph Road, just north of Wheaton Regional Park. Police said the circumstances remain under investigation. They said the driver, Sommai Tangchaiburana, who lives less than a half-mile from where he crashed, was pronounced dead on the scene.

In Virginia, police are investigating a fatal crash that involved a motorcycle and car in the southbound lanes of Interstate 95 in Prince William County on Sunday night

Based on witness accounts, Virginia State Police said the driver of a Suzuki motorcycle was weaving in and out of traffic when it struck a BMW sedan around 7:30 p.m. The driver of the motorcycle was thrown from the vehicle and was pronounced dead at the scene. The driver of the BMW and a passenger were not injured.

Police said they had not reached the victim’s family as of early Monday and his name was not immediately made public. The crash shut down all lanes of the major highway on Sunday night.

Also in Prince William, a motorcyclist and his passenger were killed when the cyclist, who police said was speeding, ran a red light and collided with an SUV about 5 a.m. Saturday in Gainesville.

Police said James Edward Beach II, 41, of Gainesville, and his passenger, Shannon Nicole Meyer, 22 of Bristow, were thrown from the 2006 Kawasaki Ninja. Beach died at the scene; Meyer died at a hospital.

Police said Beach was headed south on Lee Highway approaching Heathcote Boulevard and sped into the intersection without stopping at a red light. Beach’s motorcycle struck the rear of a 2010 Toyota Highlander whose driver had exited Interstate 66 and was crossing Lee Highway. Police said the 63-year-old driver of the Toyota had the green light. He was not injured.

Authorities said they are investigating whether alcohol was a factor in the crash. Both drivers were wearing helmets.

Donna St. George contributed to this article