It’s been a bloody new year so far in this violence-racked city, leaving authorities stunned and apparently speechless. Three teenagers in school uniforms were mowed down by automatic-weapons fire Wednesday. Another youth was shot multiple times last week as he sat in his car outside his parents’ upscale home.

Four people were decapitated, at least 10 people were killed in drive-by attacks, and five people were kidnapped, including two security guards and a prominent businessman.

Just a few months ago, Tijuana was hailed by some as a success story in Mexico’s war on drug cartels. Top officials from the U.S. and Mexico, including President Felipe Calderon, praised the city’s efforts as a model for the rest of the country.

The city’s leading crime fighters -- Army Gen. Alfonso Duarte Mugica and Secretary of Public Security Julian Leyzaola -- were named “men of the year” by Baja California’s leading news weekly. Authorities boasted that they were closing in on the city’s notorious crime boss, Teodoro Garcia Simental.

Now the bodies are piling up at the morgue again, and authorities appear dispirited by the turn of events. After the drive-by shooting of the three teenagers -- two boys and a girl -- outside their high school, authorities didn’t even hold a news conference.

“What are they going to say? They have no answers,” said Vicente Calderon, a veteran journalist who runs the local news website Tijuanapress.com.

Narco-violence has flared regularly since early 2008, when war broke out between rival factions of the Arellano Felix drug cartel. That year, the city’s homicide toll peaked at 844.

By the middle of 2009, however, the crime rate had receded as the warring gangs were believed to have reached a truce. Mugica, the military commander, paraded captured crime bosses through the Morelos military base downtown, and Leyzaola continued his purge of corrupt officers from the police force.

Mayor Jorge Ramos’ “state of the city” speech in November emphasized Tijuana’s progress against organized crime and the presentation included video of favorable comments from U.S. Ambassador Carlos Pascual and San Diego Mayor Jerry Sanders.

Since December, however, the violence has surged. The rival gangs appear to have broken their truce and are, at times, employing different and deadlier tactics.

Attackers have firebombed police cars and a funeral home with Molotov cocktails. They’ve shot up a hospital. Women are increasingly targeted. At least two of the recent beheading victims were women, one of whom was left naked outside a cemetery, a narco-message left between her legs.

Although most of the victims remain young men -- typically foot soldiers or drug dealers -- gunmen seem more willing, perhaps deliberately, to kill anyone associated with their targets.

“These acts of violence appear more and more like narco-terrorism,” said Victor Clark, the director of the Binational Center for Human Rights in Tijuana.

In late December, the government seemed to score a major victory. Gilbert Sanchez Guerrero, a former police officer and top lieutenant for crime boss Garcia, was arrested in an early morning raid at his upscale condominium in Ensenada.

His apprehension led to the arrests of at least seven more Tijuana police officers suspected of corruption.

But, as in so many cases in Mexico’s battle with organized crime, the blow was followed by another round of bloodshed, including an attack on New Year’s Eve, when gunmen broke into a home and killed an elderly couple and two other people.

Last week, 17-year-old Jose Fernando Labastida Fimbres, the grandson of a supermarket magnate, was shot as he sat in his Audi outside his home in a hillside neighborhood. A student at Mater Dei Catholic High School in Chula Vista, a San Diego suburb, the youth was memorialized by hundreds at a local church.

Two days later, gunmen wielding AK-47s shot dead the three teenagers, who had just finished final exams at Ricardo Flores High School.

Scores of students witnessed the gunmen’s car creep up on the teenagers’ vehicle and open fire, sending their Jeep Cherokee into an electrical pole as nearby students scrambled for safety.

Though media reports, citing anonymous sources, say Labastida Fimbres and one of the other teens may have had links to organized crime, authorities have made no statements on the motives.

Officials at Ricardo Flores High School, located in a tough east Tijuana neighborhood, do random drug tests and searches of students’ backpacks, but teenagers said those precautions aren’t enough anymore.

As students lingered outside school last week, many said they choose their friends with great care now and don’t get into a car unless they know the person driving it.

“We’re scared it could happen again,” said Myra Zamudio Guzman, a 17-year-old who saw the shooting.

Through all the recent violence, law enforcement officials have been mostly silent. To some observers, their reticence betrays a sense of impotence. It’s as if authorities have exhausted their tough rhetoric, they say.

One of the few government officials who made a public appearance last week was Baja California’s secretary of tourism. Oscar Escobedo Carignan announced a public relations initiative to improve the city’s image.

The negative portrayals are unfair, he said, blaming the media and citing per-capita crime figures that he said supported his case:

“We [Tijuana] finish with 20 homicides per 100,000 people. Brazil gets 150 homicides, and they get the Olympics.”

richard.marosi@latimes.com