The bound, beaten bodies of 2 men were found hanging by their necks from a highway overpass in northern Mexico on Wednesday, along with a handwritten message from a drug cartel.
The men's hands were tied behind their backs, and shell casings at the scene in Los Mochis suggest the killers fired at the victims as they were hanging by their necks, said Sinaloa state prosecutors' spokesman Martin Gastelum. The cause of death was still under investigation, however.
Nearby, a message written on a piece of cardboard said in part, "this territory already has an owner." The message appeared to be from the Beltran Leyva drug cartel, whose main leader, Arturo Beltran Leyva, was shot to death in a confrontation with Mexican marines on Dec. 16.
The message suggests his death may have unleashed a turf battle for control of areas controlled by his gang.
Sinaloa is considered the home base of some of the most powerful crime lords in Mexico, where drug-related violence has killed more than 15,000 people nationwide since President Felipe Calderon launched an offensive against cartels in late 2006.
Late Tuesday, gunmen attacked a car dealership and adjacent hospital in the border city of Tijuana, forcing the evacuation of some patients.
Baja California state prosecutors said nobody was hurt.
The attackers doused about 10 cars at the dealership with gasoline and set them alight. Cartels commonly extort "protection" fees from businesses, which are sometimes firebombed if their owners refuse to pay.
Hospitals, meanwhile, have been attacked by drug gangs seeking to finish off wounded rivals. In the past, the facility targeted Tuesday treated people wounded in shootouts.
To the east in the border city of Ciudad Juarez, in Chihuahua state, authorities said Wednesday that security forces arrested a kidnapping suspect after an armed showdown that closed a border bridge to Texas for about two hours.
Chihuahua state prosecutors' spokesman Arturo Sandoval said shots were fired Monday night as the suspect tried to flee over the Zaragoza bridge to El Paso. No injuries were reported.
Sandoval the man was suspected in the attempted abduction of a 15-year-old girl.
Also Wednesday, prosecutors reported finding the bodies of four men and a woman on a dirt road on the outskirts of Ciudad Juarez.
About 2,500 people have been murdered in the border city this year, making it Mexico's deadliest.