"El Duke," whose real name was Elider Varela, had spearheaded a program to try to get poor kids in the neighborhood, called Comuna 13, off the streets and away from drugs and crime.

"Comuna 13, I am there with you I am so sad about El Duke's murder," Grammy-winning rocker Juanes, who is from Medellin, said in a message on Twitter.

The rapper was gunned down as he strolled around his neighborhood, one of the many poor districts perched on the hillsides surrounding Medellin, his grieving widow told local media.