Gunmen shot and killed a soldier and wounded another in the outskirts of this violent border city, authorities said Friday.

Army Capt. Agustin Salazar was killed and an unidentified soldier was wounded late Wednesday after being shot while they were riding in a sports utility vehicle near a military checkpoint, Nuevo Laredo police said in a press release. The Mexican army declined to comment.

Nuevo Laredo police and state investigators who responded to the shooting saw a large amount of dollars, assault rifles and a grenade launcher inside the soldiers' car but were unable to investigate further after military personnel ordered them to leave the crime scene, the release said.

Salazar is the fourth person killed in apparent drug-related violence in Nuevo Laredo since the beginning of the year, police said.

On Thursday, police found the body of an unidentified man who had been tortured and shot in the head near the city's military barracks, state investigator Ricardo Mancillas said.

Violence in northeast Mexico has been on the rise since March 2003, when reputed drug lord Osiel Cardenas was arrested during a shootout in Matamoros, across the border from Brownsville, Texas. Another accused drug lord, Joaquin "El Chapo" Guzman, has been fighting smugglers loyal to Cardenas to gain access to smuggling routes into the United States.

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