MONTERREY, Mexico (AP) -- Gunmen killed a town mayor near the drug-plagued industrial city of Monterrey, authorities said Friday, the fourth mayor in northern Mexico to be murdered in little more than a month.
Prisciliano Rodriguez Salinas was gunned down late Thursday as he was leaving his house with a personal employee in the town of Doctor Gonzalez, about 30 miles (50 kilometers) east of Monterrey, the Nuevo Leon state Attorney General's Office said.
The employee, Eliseo Lopez Riojas, who was picking up equipment from the mayor's house, was also killed when gunmen in a white car waiting outside started firing. Investigators found 19 shells from two different weapons at the scene. The mayor was shot seven times.
Drug gangs warring for territory and smuggling routes in northern Mexico have increasingly targeted political figures in the region, though the attorney general said aspects of Rodriguez's killing were uncharacteristic of gangs.
"The act, in terms of waiting for the mayor outside his house ... is not a very common tactic for organized crime," state Attorney General Alejandro Garza y Garza said. "So we're not ruling out any line of investigation."
Garza y Garza said he was unaware of any threats against the mayor. Town clerk Reinaldo Campos also told The Associated Press that he knew of no threats.
Police officers from the town were taken to Monterrey for questioning about the killings, though Garza y Garza said none were under arrest.
Hermenegildo Linares Robledo, assistant to the town clerk, said normal activities at the town hall had been suspended and confirmed that state police were patrolling the streets, though there were no soldiers in view.
"There are very few people in the streets," he told the AP. "Right now the mood is tense and quiet."
Nuevo Leon Gov. Rodrigo Medina said that his administration "will not be intimidated, that we do not give in."
President Felipe Calderon condemned the attack and sent his condolences to the family as his government reiterated its commitment to the security of all Mexicans. The government has attributed the spike in violence in the border states of Nuevo Leon and Tamaulipas to a breakup between the Gulf and Zetas cartels.
Monterrey-area mayor Edelmiro Cavazos was kidnapped in August and his body dumped three days later. Seven police officers who authorities said were paid monthly salaries by the Zetas were arrested in connection with that killing.
It was followed two weeks later by a fatal attack on Mayor Marco Antonio Leal Garcia in Hidalgo, Tamaulipas.
Hooded gunmen shot to death Mayor Alexander Lopez Garcia in the town of El Naranjo in San Luis Potosi state on Sept. 8. The methods used in all three slayings were similar to those used by Mexico's drug cartels.
In June, gunmen killed the leading gubernatorial candidate in Tamaulipas.
Meanwhile, a congressman-elect sought by federal authorities for alleged drug ties slipped into the Chamber of Deputies on Thursday and took his oath of office - making him immune from apprehension and prosecution for the duration of his term.
Julio Godoy was elected to congress in July 2009 and went into hiding after he was charged days later with protecting La Familia cartel in the western state of Michoacan.
The congressman called himself the innocent victim of an attack by the federal government, saying, "I am not a criminal."
The president of the Chamber of Deputies, Jorge Carlos Marin, said a judge ruled that Godoy maintains his political rights despite the warrant for his arrest.
Godoy was elected as a candidate for the leftist Democratic Revolution Party, which governs Michoacan and has been one of the biggest critics of President Felipe Calderon's strategy against organized crime.
More than 28,000 people have been killed in drug-related violence since Calderon launched his attack on drug cartels in late 2006