Jonathan Chappell, Jamel Williams and Miriam Khalifah are charged with a robbery that happened on Monday.
Police say the 22-year-old Chappell threatened a man with a shotgun on Edgemere Avenue and Linwood Street in Hempstead and demanded the victim's cell phone.
He took off with the phone and cash and fled the scene in a 1996 Chevy Blazer occupied by the 28-year-old Williams and 31-year-old Khalifah.
Police say two of the suspects are linked to an attempted robbery two weeks ago in Uniondale and may be linked to as many as seven robberies with 12 victims since August 30.
Four of the victims were Hofstra students.
Police say the suspects target young people walking home at night between midnight and 4 a.m.