Danbury Police received several calls from concerned residents yesterday after hearing gun shots fired.  Police say the initial call was about the hill behind Home Depot, but there was also one about Stadley Rough Elementary School.  Police say it turned out to be outdoor firing range practice at the Federal Correctional Institution.  FCI Danbury does not need to alert the Danbury Police Department when the range is being used, but police called to see if they were the source of the noise.  Norwalk police were practicing with long guns at the time.  Danbury officers were sent to the school and the area of the business as a precaution.