Two pedestrians, ages 84 and 78, were struck and killed by vehicles Friday in Milton and Fitchburg, said authorities. James Aho, 84, was walking with MaryAnn LeBlanc, 67, both of Westminster, at Simons Road and Westminster Street in Fitchburg when they were hit at about 5:47 p.m. Friday, said Tim Connolly, spokesman for the Worcester District Attorney’s Office. Aho was killed and LeBlanc hospitalized with serious injuries, said Connolly. At about 4:51 p.m. Friday, a 78-year-old Milton woman was killed as she crossed Highland Street in Milton, said David Traub, spokesman for the Norfolk DA’s office. Her identity was not released. No charges have been filed in either case.