Puerto Rican name for a group of residential buildings at low-cost, generally paid by the government. The name is given is either because it is a group of "casas" or homes (therefore "case-rio") or after the word "caza" meaning hunting, because these buildings are famous, especially in the metropolitan area and Ponce, for daily shootings and killings between drug dealers and mobsters. Though most people living in "caserios" are decent people who cannot afford to pay a more expensive home or lease an aparment that may cost about $500 or more per month because do not have a job or do the earn enough, most of them have a minor group of people who own drug dealerships (or "puntos de drogas") and within a caserio itself there may be more than one dealership which is the cause for daily fights and shootings between rival groups. A caserio in Puerto Rico is similar or equivalent to a ghetto in the United States, though ghettos can be significantly more dangerous, since caserios in areas outside San Juan metro area and Ponce do not have that much violence.
"Hay demasiado tiroteo en ese caserio" (There are way too much shootings in that caserio).