Prosecutors in El Salvador have arrested five police officers, 16 gunmen and a police administrative employee for allegedly killing street gang members.

There have long been reports of death squad-style killings in El Salvador, where street gangs have been battling police.

The country's attorney general said Friday the gang arrested this week appears to have been dedicated to crime in general, including murder for hire and robbery.

Douglas Melendez said "an isolated group" of police officers appears to have cooperated with the gang since 2015 by providing information or vehicles to the killers.

The head of the country's Human Rights Commission says that death squads have operated in El Salvador.

Miguel Montenegro says "this is why we should strengthen our justice system."