At about 18:02 EST, a Dassault DA-900 overran the runway at Barnstable Municipal airport The four occupants were uninjured but two occupants of motor vehicles on a public road were slightly injured. The PIC said the crew briefed the VOR runway 6 approach prior to departing LGA. When they arrived at HYA they discovered the weather was below minimums for the VOR approach. Winds at the time were from 020 at 21, gusting to 34. The PIC requested the ILS Runway 24 approach and decided to land the airplane if the braking action was reported as fair and discontinue the approach if it was reported as poor. He said the controller reported braking as either fair to poor or poor to fair. He landed and applied maximum reverse thrust and braking. The airplane departed the end of the runway, slid through the Runway 24 localizer antenna array and a chain link fence, crossed a two-lane road, struck three vehicles, continued into a parking lot and struck four concrete parking barriers, three cement light fixture bases and two parked vehicles. An FAA inspector saw the airplanes tire tracks began about 2,640 feet from the approach end of the runway and about 2,785 feet from the departure end.