SAN YSIDRO, Calif. — Assaults against U.S. Border Patrol agents nearly doubled along the Mexican border over the last year as patrols cracking down on drug trafficking and migrant smuggling encountered increasing resistance -- including the use of rocks, Molotov cocktails and gunfire.
At least 687 assaults against agents were reported during the fiscal year that ended Sept. 30, up from the previous year's total of 354 and the highest since the agency began tracking assaults across the Southwest border in the late 1990s, according to Border Patrol officials.
Most assaults occurred near urban smuggling havens such as Nogales, Ariz., and Tijuana, but cross-border skirmishes took place from remote California deserts to the banks of the Rio Grande in Texas.
In many attacks, smugglers hurled softball-size rocks or fired high-powered slingshot devices loaded with marbles and ball bearings. Some tried to run over agents with vehicles.
In some cases, smugglers and migrants fought with agents and tossed wooden pallets to block their pursuers. Dented and damaged vehicles, windshields shattered, sat in Border Patrol parking lots.
In Tucson and San Diego, the most violent sectors, agents reported being shot at 43 times -- up from 18 the previous year. No agents were killed, but three were shot in the leg. At least 20 more were hospitalized, many with head injuries from rocks.
Agents fatally shot five suspected smugglers in the Tucson and San Diego sectors. In one recent case, officials said, an agent struggled with and killed a man who was armed with a semiautomatic weapon and was suspected of waiting to pick up migrants.
Officials attribute the increased number of assaults to rising frustration among drug and immigrant traffickers, who have seen traditional smuggling routes blocked by the border buildup. About 11,000 agents -- more than ever -- patrol the 2,000-mile border with Mexico. Stadium lighting, sensors, remote cameras and triple fences protect some frontiers.
"They're feeling they have to fight their way through now," said Agent Jim Hawkins, a spokesman for the agency's Tucson sector. "We're taking their livelihood away from them, so they're getting angry and desperate."
On one stretch of border near San Diego, rock-throwing and other violent acts have become so common that officials plan to erect signs warning that assaulting agents is against the law.
The recent surge, officials say, doesn't match the level and intensity of violence in San Diego County in the early to mid-1990s, when agents wore riot gear and formed special units to disperse crowds of migrants and to combat widespread banditry.
The recent violence has spread out across the Southwest as illegal immigration corridors have shifted. Most assaults occur in Arizona and California, where borders have been heavily fortified.
Agents and experts expect the hostile climate to intensify as the border becomes increasingly difficult to cross.
"It's a combustible mixture," said Wayne Cornelius, director of the Center for Comparative Immigration Studies at UC San Diego. "It's inevitable there will be an escalation of violence on both sides, because the traffic hasn't diminished ... and the desperation of those trying to get in is just as great as it has ever been."
While immigrant smugglers mostly throw rocks to distract agents, drug traffickers are more likely to use weapons and committed the most serious assaults in the past year, officials say.
In June, two agents following a rural smuggling trail east of Nogales fought a fierce gun battle with several suspected drug runners. Both agents suffered leg wounds but kept returning fire, officials said. The suspects fled back to Mexico.
In another clash, an agent patrolling a rugged area east of San Diego over the summer came under a hail of gunfire as he approached a vehicle being loaded with drugs. More than 23 bullets, believed to have been fired from Mexico, hit the agent's vehicle. He suffered a minor leg wound.
Most assaults occur along highly fortified border areas across from hillside urban shantytowns. Smugglers throw rocks or fire slingshots or paintballs at agents from the higher vantage points. They flee when Mexican authorities arrive or when agents fire back with launchers that shoot exploding balls filled with pepper spray.
Agents say Border Patrol measures are often countered with more aggressive tactics from the smugglers.
"It's just a matter of time before they start shooting at us. We're making it too hard for them," said Matilde Torres, a supervisory agent who works a rock-strewn, nine-mile stretch across from Tijuana's notorious Colonia Libertad neighborhood.
After agents began using pepper ball launchers a few years ago, smugglers countered with slingshots. Agents in turn began aiming the launchers at torsos instead of feet.
Torres, standing about 50 feet north of the border fence, pointed to ramshackle buildings in Tijuana that bore the marks of dozens of bursts from pepper spray rounds.