ROBERT SIEGEL, host:
Now we're going to hear from Tijuana about killings that have shocked people on both sides of the U.S.-Mexico border. In two separate attacks last week, four teenagers were murdered.
Amy Isackson covers the border for member station KPBS in San Diego, and she sent this story.
AMY ISACKSON: I'm standing here on a street in one of Tijuana's most exclusive neighborhoods. Many of the border cities' most prominent families live here. The homes are big. They're not mansions, but they look very comfortable. Here in the street it's difficult to feel totally at ease. On this thick, pink cement wall - it's in front of one of their homes - you can see where the bullets hit. Across the street, you can see the chalk circles on the sidewalk where the bullet casings fell. Last week, gunmen pumped 59 shots into a late-model black Audi here. The driver, his name was Josefo Labastida Fimbres, was 17.
Unidentified Man: Unfortunately, crime doesn't respect (unintelligible).
ISACKSON: We can't identify the man who's talking, for security reasons. His family has been friends with the Fimbres' through three generations.
Unidentified Man: They're a very, very big family. All of them have been very, very involved in every aspect of Tijuana history and life. Hardworking country with - economically, politically, charity-wise.
ISACKSON: He says 17-year-old Josefo had come out of his shell during the last couple of years. Josefo was going to high school in San Diego. He was a good golfer. And he had a lot of friends - more than 100 of them have left messages on a Facebook memorial. They wrote about chemistry class, a ski trip and a visit to Sea World.
Unidentified Man: But, unfortunately, he got a little sidetracked, probably by the influences from friends and probably he wasn't looking for it, but was drawn into it.
ISACKSON: Mexican law enforcement authority say Josefo's killers were tied to organized crime. In Tijuana, that means drug cartels.
(Soundbite of vehicles)
ISACKSON: Across town, two days later, it happened again. Three more teenagers were ambushed, this time outside their high school. Nineteen-year-old Orlando says he saw it all happen.
Mr. ORLANDO: We were going down the hill and there was a noise, like duh, duh, duh, duh.
ISACKSON: School had just let out. He says a small, white car drove by and gunfire burst out of it.
Mr. ORLANDO: I got sick. I got sick because I looked at - they're all shot. I got sick up the street, after that, in my house. You know, (unintelligible) not coming back.
ISACKSON: The Baja California attorney general's office says the hit men used machine guns, the kinds that drug cartels like. These four murders came during a week when more than 30 people were killed in Tijuana, three severed heads were found dumped around the city. This kind of gruesome drug cartel violence had died down for most of last year. And some were congratulating Tijuana for regaining control. That was a mistake.
Dr. DAVID SHIRK (Fellow, Woodrow Wilson International Center): If anything, the recent uptick in violence shows us just how little control authorities have over the rate of violence among the cartels.
ISACKSON: David Shirk is a fellow at the Woodrow Wilson Center in Washington, D.C.
Dr. SHIRK: Lulls and surges really appear to have more to do with what's going on between and within the cartels than anything the federal government in Mexico has done.
ISACKSON: While no one seems to know what's going on within the cartels in Tijuana, the fear is that criminals have rewritten the rules of the drug war. Under the new rules, anyone associated with the cartel, their families and even teenagers can be targets.
For NPR News, I'm Amy Isackson in San Diego.