A 16-year-old girl was killed Friday as she was crossing Long Island Rail Road tracks in Garden City.Officials say Jacqueline Vincent, of Garden City, was with friends after a party around 12:30 a.m. They say the group was trying to cross the tracks when Vincent fell on the third track and was electrocuted.Residents say kids frequently use the tracks west of the Garden City train station as a shortcut. One resident said he hopes the tragedy will make lawmakers consider fences to block people from getting on the tracks.MTA police are still investigating the accident and plan on performing an autopsy to determine whether alcohol was a factor. Friday would have been Vincent's final day in school before summer break.