Sgt. Arthur Betts, a State Police spokesman, said a final accident report could take months to complete. Police said Monday that they had not yet determined what role Raeburn, the 26-year-old driver of the Impala, played in the incident.

 But out on the highway, physical evidence suggested how the scenario unfolded. Just west of where the ramp from Ingleside Avenue merges into westbound I-70 at milepost 4B, two parallel pairs of recent skid marks blackened the pavement as if made by racers coming out of a starting gate with wheels smoking.

Sigismondi said he frequently hears tires squealing on the interstate. “They do black burnouts and something lights up as they’re taking off,” he said.

About a quarter-mile down the highway, near the I-70 interchange with Interstate 695, another set of skid marks showed where a driver had lost control of his vehicle and left the roadway. Tire tracks showed where at least one vehicle went down a small embankment and crashed into some small trees. Signs could be seen of recent rescue activity, including a discarded neck brace and black latex gloves, and broken windshield glass littered the scene.

Police said the Impala driven by Raeburn struck a 2004 Cavalier owned by Duffy, who was standing outside his vehicle. The Cavalier was pushed into the rear of a 1995 Acura Integria owned by Henderson, who had been standing with Abernathy. Both were pronounced dead at the scene.

The section of I-70 east of the Baltimore Beltway is a vestige of an earlier plan to extend the highway into the heart of Baltimore. That plan was canceled in the 1980s because of environmental concerns and community protests. Besides the park and ride, that leg of I-70 serves Security Boulevard and Cooks Lane.