Volodymyr Zhukovskyy, 23, was driving a company vehicle hauling a trailer on a highway in Randolph, police said, when he slammed into a group of 10 motorcyclists. State authorities described the wreckage as the worst they had ever seen.
Zhukovskyy was arrested at his home in West Springfield, Massachusetts, on Monday morning, the New Hampshire deputy attorney general's office said in a statement.
It was not immediately clear if Zhukovskyy had retained a defense lawyer.
The National Transportation Safety Board on Saturday said it was sending a team to the site of the crash to conduct a safety inquiry and work with local authorities, who are doing their own investigation.Officials said on Sunday that the victims, five men and two women ages 42 to 62, all died of blunt trauma. The group was associated with the Jarheads Motorcycle Club, which consists mostly of U.S. Marine Corps veterans and their relatives.