— Witnesses say a decommissioned ambulance used to haul dive equipment for the Dennis Fire Department rolled backward and struck two firefighters at Sheep Pond yesterday, Brewster police Capt. The Cape Cod Regional Crash Reconstruction Team is examining the 1990 GMC decommissioned ambulance for any mechanical problems, Dennis Fire Chief Mark Dellner said. Dennis Firefighter-Paramedic Dan O’Connell, a member of the Dennis Fire Department for 17 years, already has been released from Cape Cod Hospital, Dellner said.