The hometown of some of the accused killers of Border Patrol agent Brian Terry has been engulfed in serious drug-war violence in recent days.

El Fuerte, Sinaloa — suspected hometown of the Osorio-Arellanes brothers accused in the killing — was the site Monday of an ambush of state police. Thirty to 50 armed men attacked a convoy of police vehicles, killing seven officers. Four attackers also were killed in a firefight in which at least 1,000 rounds were fired.

Manuel Osorio-Arellanes listed El Fuerte as his hometown in court records. Brothers Rito and Heraclio are also defendants in the case, as is their brother-in-law, Jesus Rosario Favela-Astorga.

El Fuerte is a municipality in north-central Sinaloa, just south of the Sonora border. The whole region has been the scene of fighting in recent months.

Fighting broke out in the neighboring municipality, Choix, in late April and has occurred sporadically ever since, leaving dozens dead as rival criminal groups fight for supremacy. The police chief of Choix was murdered June 29, and the army and police have deployed to the town to try to stop the violence.

In Tucson Monday, authorities declined to specify how they were pursuing the four fugitives accused of killing Terry. But James Turgal, head of the FBI's Phoenix division, and U.S. Attorney Laura Duffy both said they had been working with state, local and military officials in Mexico, as I mentioned in Tuesday's story.

Duffy also said specific efforts at capturing the suspects occurred in April and June, but she wouldn't say where those took place.