The video, seen on screens across the country, seemed so clear. A Range Rover collides with one of scores of motorcycles that had commandeered the Henry Hudson Parkway. A confrontation ensues, then another crash and finally a chase that ends with the S.U.V. driver being attacked as his wife and toddler sit helplessly.

But the crispness of the helmet-camera images, captured by a rider in the pack of motorcyclists, gave way on Tuesday to a painstaking effort by investigators to piece together a frantic sequence of events that stretched over many minutes and several miles and that involved dozens of suspects and witnesses.

The police said on Tuesday that they had charged two motorcyclists; one of them had turned himself in. A third rider was hospitalized, according to a family representative, who said the man’s legs had been broken when the Range Rover plowed into the crowd of motorcyclists gathered around the one who had been knocked to the ground in the initial collision.

The 33-year-old man who was driving the Range Rover was staying out of sight on Tuesday, even as his confrontation with the motorcyclists became national news and had authorities raising concerns about motorcycle groups that try to take over roads for impromptu races and stunts. Detectives were looking into the possibility that the motorcyclists involved in Sunday’s episode had been trying to clear cars from the parkway — in an effort to perform tricks and ride unencumbered — when they encountered the Range Rover. The video appears to show motorcyclists at entrance ramps, possibly in an effort to block oncoming vehicles.