Within the past week, authorities in the southwest Valle del Cauca province reported a massacre of 13 people in the Pacific port city of Buenaventura, and four members of a family killed in the town of Roldanillo, reported El Pais. The newspaper reported that the 17 deaths are a sign of attempts by the Urabeños to take control of drug trafficking routes in Valle del Cauca, a province where authorities estimate the trade is worth over $5 million a month.

So far, the Urabeños are targeting the cities of Tulua and Buenaventura for expansion, El Pais reported, with Buenaventura’s access to the Pacific highly prized. At least 20 Urabeños members are believed to be operating in the latter city.

Police attributed at least 70 percent of the 223 homicides in Tulua and Buenaventura so far this year to the struggle for control of Valle del Cauca’s drug trade.

InSight Crime Analysis

Though the northern-based Urabeños have reportedly had a presence in Valle del Cauca since last year, this has been primarily through alliances with Los Machos and former Cali Cartel member Victor Patiño, both rivals of the Rastrojos. Now, they appear to have been emboldened by the fall of the Rastrojos' three principal leaders this year and are actively seeking direct control over the drug trade in the area. The removal of Luis Enrique Calle Serna, his brother Javier and Diego Perez Henao, alias "Diego Rastrojo," from the picture has severely weakened the Rastrojos, with no clear successor poised to take over.

The Urabeños' push will be helped further by the demobilization of 150 Rastrojos members, which was arranged as part of the surrender deal of Luis Enrique Calle Serna last month, reported El Tiempo.

There is also the spectre that violence in the region could erupt further due to warring factions within the Rastrojos. Semana reported last month that officials in the province feared a new mafia war sparked by turmoil within the gang after a spate of killings in the province.