A 66-year-old motorcyclist from Indiana was killed Friday night in a collision with a vehicle near the Mall, D.C. police said. The crash occurred shortly after the end of a vigil at the Vietnam Veterans Memorial sponsored by the Rolling Thunder motorcycle group.

It could not be determined whether the victim, George Hillis of North Lake Village, Ind., was taking part in the event, which draws thousands of motorcyclists from across the country to the District over Memorial Day weekend.

About noon Saturday, Virginia State Police said, two related accidents involving four motorcycles on Interstate 66, west of Nutley Road in Vienna, left one person in critical condition with injuries described as life-threatening, another in serious condition and two with minor injuries. All four were taken to Fairfax Inova Hospital.

State police spokeswoman Corinne Geller said the motorcyclists were from New York and Ohio and were headed as a group to Washington to watch the Rolling Thunder parade around the Mall on Sunday.

She said they were not participants.

Geller said that two Harley-Davidson operators braked for stopped traffic and that a third Harley-Davidson rear-ended one of them.

A fourth Harley crashed as the operator tried to avoid the pileup, Geller said.

Friday’s accident in the District occurred about 11 p.m. at 23rd Street and Constitution Avenue NW, near the Lincoln and Vietnam Veterans memorials. Officer Hugh Carew, a D.C. police spokesman, said Hillis was operating a 2003 three-wheel Harley-Davidson and was turning off 23rd Street onto westbound Constitution Avenue when he collided with a Chrysler Sebring that was southbound on 23rd Street.

Carew said Hillis was pronounced dead at a hospital. A person who answered the phone at Hillis’s home said relatives were on the way to Washington to claim the body but declined to comment further.

Police said the accident remains under investigation and would not say whether investigators have reached a conclusion as to which driver was at fault.