RIO DE JANEIRO - Homicides are rising in Brazil’s north and northeast, with 18 of the 20 most violent cities of more than 100,000 inhabitants located in those two regions.

A report by the Brazilian Institute for Applied Economic Research published Monday indicated that the most dangerous municipality was Maracanaú, in Ceara state, with a homicide rate of 145.7 per 100,000.

It is followed by Altamira, in Para state, where 58 inmates were killed last week in a prison riot, 16 of them decapitated.

Partly explaining this geographical divide, the report said, is the ongoing war between criminal organizations to control drug trafficking routes through the Amazon, a multibillion-dollar trade.

Cities with higher homicide rates also had much lower incomes, school attendances, job opportunities and worse housing conditions compared to their more secure counterparts.