A gunman inside a moving car shot a Massachusetts man in the arm as both drove north on Interstate 93 in the Randolph-Braintree area around 1 a.m. Sunday, Massachusetts State Police said. The victim, a 30-year-old man, was taken to Boston Medical Center and was expected to survive. Trooper Todd Nolan, a State Police spokesman, said authorities did not have a description of the shooter’s vehicle and no information on whether road rage was a factor. Witnesses are asked to call the State Police communications office at 508-820-2121 or the Milton barracks at 617-698-5840.Jeremy C. Fox can be reached at email@example.com. Follow him on Twitter @jeremycfox.