Mexican officials believe the massacre of nine American woman and children may be related to a clash between two gangs, the Sonora-based Los Salazar and Chihuahua-based La Línea. According to The New York Times, officials will now be focusing their investigation on the two rival groups who are fighting for control in northern Mexico. The two groups apparently had a fatal shootout near the U.S. border before the attack on the Mormon family. Gen. Homero Mendoza Ruiz, Mexico’s chief of staff for national defense, also said two of the victims were driving suburbans that were commonly used by criminal gangs in the region.

Public security official Alfonso Durazo also announced Wednesday that the suspect previously arrested in the attack was also determined not to be linked to the killings. The suspect was arrested Tuesday in the border city of Agua Prieta with assault rifles on Tuesday, according to the Associated Press.