SAN SALVADOR — El Salvador, a small Central American nation whose government has spearheaded a brutal crackdown on criminal gangs, is seeing one person go missing each day, according to a group of non-governmental organizations (NGOs) citing prosecutors’ data.

The attorney general’s office counted 366 people who went missing in the 12 months to May 31 this year, the Working Group for Missing Persons in El Salvador, an association of nine NGOs, reported on Wednesday.

El Salvador’s…