All of the incidents were reported between 10:40 p.m. and midnight on Thursday.
Police say the first robbery occurred in the unit block of E. North Street; the second occurred in the area of Dellwood St. and E. Union Blvd.; the third occurred in the 400 block of Main Street and the fourth robbery occurred in the 1600 block of Jill Street.
The victims told police they were threatened robbed by a group of young men in a green Ford Focus, with investigators adding that one woman was assaulted.
Police began a search for the car and found it parked on Fritz Drive. Five young men were in the car, police said, and most of them fled the vehicle.
The driver of the car, Johnnie Johnson, 19, never made it out of the car and was arrested.
Two others, 18-year-old Danny Stafford and a 15-year-old boy, were arrested a short distance away.
Johnson and Stafford were committed to Northampton County Prison pending county court action.
The15-year-old was committed to Northampton County Juvenile Detention pending county court action.
Anyone with information or knows the identities of the other two males involved is asked to contact the City of Bethlehem Police Communication Center at 610-865-7187 and/or Det. Brad Jones at 610-865-7146.