A gang of gunmen killed an off-duty U.S. airman and five other people early Wednesday at a bar in the Mexican border city of Ciudad Juarez, authorities said.
Meanwhile, gunmen assassinated an army general recently named police chief of Garcia, a town in the northern state of Nuevo Leon. It the latest attack against a military official appointed to take over municipal police forces, which President Felipe Calderon has acknowledged are plagued with corruption.
All 70 officers of the Garcia police force were questioned in the attack, Nuevo Leon Gov. Rodrigo Medina said at a news conference. He said soldiers and state police will be sent to patrol the town.
There was no immediate information on a motive for the attack that killed the U.S. airman at the Amadeus bar in Ciudad Juarez, which also left a seventh person wounded, said Arturo Sandoval, a spokesman for prosecutors in northern Chihuahua state. But the methods bore the hallmarks of attacks by drug cartels.
The attacks raised to 30 the number of homicides in Ciudad Juarez in just four days. The city is one of the world's most violent, with 2,100 people killed in drug-related attacks this year alone.
Staff Sgt. David Booher, assigned to the medical unit of the 49th Fighter Wing at Holloman Air Force outside Alamogordo, New Mexico, about 90 miles (145 kilometers) north of Ciudad Juarez, was among those killed in the bar, the U.S. Air Force said.
Earlier this year, the 12th Air Force barred airmen from traveling in Mexico's Chihuahua state. Soldiers from Fort Bliss, just outside El Paso, Texas, across the border from Juarez, also are barred from going to Chihuahua.
Prosecutors later said four men were found dead outside the perimeter wall of Pedro E. Medina Gonzalez primary school in another part of Ciudad Juarez. Classes were in session at the time.
The wall, which abuts the school's playing fields, was pockmarked by bullets. A sign posted on the government-run school's entrance said classes were suspended for security reasons.
In Garcia, gunmen killed police chief Brig. Gen. Juan Arturo Esparza as he drove to the home of town Mayor Jaime Rodriguez, who had reported a threat to his life, the mayor told Mexican media. Four others riding in the car with Esparza were also killed.
Shortly before the shooting, Rodriguez said he had called police to report that armed men had driven up to his home and warned him to be careful. Esparza was on his way to Rodriguez's home when armed men opened fire on his car, the mayor said.
Esparza had been appointed Garcia police chief just days earlier — part of a trend to name active or retired military officers to Mexico's municipal police forces.
In April, an army colonel was shot to death less than three weeks after taking over the local police force in Piedras Negras, a Coahuila city across the border from Eagle Pass, Texas. In August, an ex-general serving as police chief in the northern city of Monclova escaped an assassination attempt that killed three of his bodyguards.
Esparza's assassination came as the new police chief of another city in Nuevo Leon vowed to fire corrupt cops. In an interview with El Norte newspaper, Gonzalo Adalid, police chief of San Pedro Garza Garcia, also promised to create incentives for loyalty so police "will not have to ask for a cent from anyone."
Last month, soldiers detained 20 police officers from San Pedro, an affluent suburb of the northern city of Monterrey, for allegedly collaborating with the Beltran Levya drug cartel.
Calderon has acknowledged that corruption permeates Mexican police at all levels. He has deployed tens of thousands of army soldiers and federal police across the country to lead the battle against cartels.